Tuesday, December 21, 2021

A Long Road to Happiness: The Story of Perrine

This post was co-written by Joan Turmelle. The use of "I" in this post refers to myself (Albertonykus), whereas "we" refers to both co-authors. A version of this post has been cross-posted to my Tumblr blog.

What's this? More than seven months without a new post, and I come back with one that's not about dinosaurs? And it's not even April 1st?! Well, I already had a different subject in mind for April 1st of next year, and I think that this post could be of potential interest to some people who might be looking for TV series to binge over the holidays, especially in these pandemic times. I also just completed a draft of an entire PhD thesis on dinosaur evolution, so I hope that even I can be forgiven for spending a little time not thinking about dinosaurs (and, believe me, it's not often that I do so). Besides, I'll be back soon enough in January with the usual reviews of the past year in maniraptoran discoveries; you won't have to wait long for more dinosaur content on this blog.

Over the last few months, I have not had much time to devote to anything other than my thesis, but taking breaks is supposed to be healthy, even for—uh, especially for final-year PhD students. And so it happened that on some of these breaks I was inspired to revisit a series I hadn't watched since my childhood, The Story of Perrine. I remember enjoying it as a child (which in hindsight is surprising in some ways), but having rewatched it recently, I'd go as far as to say that it may now be one of my favorite shows of all time.

The Story of Perrine originally aired in 1978 and was based on the 1893 French novel En Famille by Hector Malot (which has been translated into English as Nobody's Girl or The Story of Perrine). It is one of the entries in World Masterpiece Theater, a series of animated Japanese adaptations of classic children's literature. The story follows a 13-year-old girl, Perrine, as she travels across Europe with her mother Marie (who for some reason is almost always left out of promotional posters for the show), their dog Baron, and their donkey Palikare to see Perrine's paternal grandfather in France, who none of them have met before.

This anime was never dubbed into English and accordingly appears to be pretty obscure in the English-speaking world. The version that I knew as a child was the DVD release of the Mandarin dub that had aired in Taiwan (where my parents grew up). Fortunately, as of the time of writing, the original Japanese dub is available on YouTube with fan-made English subtitles, and it was through this version that I revisited the show earlier in the year.

One of the reasons I'm surprised that I sat through this series when I was little is that it's slow paced and has a very tranquil atmosphere. It's certainly not a show with constant action or epic magical quests. At the same time, it's telling a continuous narrative with strong continuity and consistent character development. The stakes in the show are rooted in the magic of reality: the way one can find joy or laughter or sorrow or great lessons even in everyday life, and how that appreciation for the mundane can be its own magic. It's a type of storytelling that I haven't seen in many other fiction shows. 

Cover art for the series soundtrack. As you can see, Marie has been left out of this one as well.

The closest comparison that comes to mind may be the Netflix animated series Hilda, which we also adore. Both shows are wholesome, down-to-earth, and sometimes very emotional series that feature precocious young girl protagonists being raised by single mothers. Other good comparisons might be the Studio Ghibli films Kiki's Delivery Service and My Neighbor Totoro. Unlike Hilda and the aforementioned Ghibli films, however, The Story of Perrine has essentially no fantasy elements at all. It really is more or less realistic fiction, such that one could probably re-enact almost everything that occurs in the series if circumstances were right. It also arguably gets a bit darker than Hilda, with permanent character deaths that are taken dead seriously. There are parts of the series that get pretty sad and bleak, though the story does ultimately have a happy ending.

The Story of Perrine was produced not long after the characteristic anime art style was popularized in the 1960s, and in some ways its character design actually deviates a bit from the "standard" anime style that is familiar nowadays. Its age shows from a technical perspective; though it evidently had the appropriate budget to portray the story as intended, there are definitely noticeable inconsistencies in the animation here and there. Even so, they are more fun things to point out instead of strong criticisms, and most certainly do not make the show any less compelling. Also amusing from a modern standpoint are the previews that play at the end of each episode, which tend to give away most of the plot of the subsequent episode—presumably symptomatic of a time without on-demand streaming services, meaning that missing entire episodes was a real possibility for viewers.

What follows are some of our thoughts on specific storylines and themes from the show. If you are at all interested in seeing The Story of Perrine for yourself, we strongly recommend that you stop reading at this point and just start watching. We would even advise against looking up anything else about the show, because nearly all the English summaries we've seen give away major events in the series. Additionally, if you'd prefer to get our thoughts in podcast form instead (along with a more detailed plot recap of the series), you can check out the review we did for our YouTube channel Through Time and Clades (embedded below).


Monday, May 10, 2021

Angels of the High Seas: The Mystifying Affinities and Origins of Tropicbirds

I have never had the good fortune of seeing living tropicbirds in person, so I can only imagine that they must look ethereal. These seabirds range from pigeon- to chicken-sized, but their long, pointed wings give them wingspans of a meter or more. Both male and female tropicbirds are clad mostly in white plumage and possess a central pair of extremely long, narrow tail feathers (as long as or longer than the rest of their body), which they flaunt to each other during aerial courtship displays.

Red-billed tropicbird in its natural state, photographed by Dominic Sherony, under CC BY-SA 2.0.

True to their name, tropicbirds spend most of their lives flying over the tropical oceans of the world, far from land. Although there are other seabirds (like albatrosses and frigatebirds) that frequent the skies above the open ocean, many of these groups undertake their long pelagic journeys by soaring effortlessly on air currents. Tropicbirds, on the other hand, travel primarily by sustained flapping flight, punctuated by only brief periods of gliding and soaring. From the air, they spot their prey (mostly small fishes and squids), and capture them by plunging from the sky with a splash before taking off again.

When these elegant aeronauts need to rest, they alight on the surface of the ocean. However, despite having totipalmate feet (webbing between all the toes on each foot), their hindlimbs are so small that they are not particularly good at active swimming. Their feeble hindlimbs also render them awkward when they return to land to breed, requiring them to shuffle along the ground on their belly, sometimes with the aid of their beak and wings.

Red-billed tropicbird resting on the ocean's surface, photographed by Steven Mlodinow, under CC BY-NC 4.0.

Fortunately, tropicbirds nest on remote islands that are typically safe from land predators. They often adopt crevices in rocky ledges as nest sites, though flat ground or forks and hollows in trees may also be used. Tropicbirds are probably at their least angelic on their breeding grounds, as competition over suitable nest sites can be extremely fierce, and many adult tropicbirds bear scars on their head as a result of such disputes.

Three species of extant tropicbird are currently recognized. In order of increasing size, they are the white-tailed tropicbird (Phaethon lepturus), the red-billed tropicbird (Phaethon aethereus), and the red-tailed tropicbird (Phaethon rubricauda). Although they are low in diversity and restricted to equatorial regions today, the fossil record reveals an ancient history and more widespread distribution for total-group tropicbirds in the past.

What may be the oldest known stem-tropicbird fossils were described by Mayr and Scofield (2016), these being a partial humerus (upper arm bone) and carpometacarpus (fused wrist and palm bones) from the Paleocene Waipara Greensand of New Zealand (about 60.5–61.6 million years old), similar in age to some of the oldest known stem-penguins. A potentially even older fossil bird that has been likened to stem-tropicbirds is Novacaesareala, known from fragmentary forelimb bones found in the Hornerstown Formation of the eastern United States (Mayr and Scofield, 2016). The age of this formation is disputed (it may date to either the Late Cretaceous or early Paleocene), but in any case the available specimens of Novacaesareala are probably too limited for a well-founded identification (Mayr, 2017).

Partial humerus of a possible stem-tropicbird from the Waipara Greensand (A–D) compared to the humerus of a white-tailed tropicbird (H–K), from Mayr and Scofield (2016).

There are, however, much better-represented stem-tropicbird taxa that are only slightly younger (by geologic standards) than these records, namely Lithoptila from the late Paleocene–early Eocene of Morocco and Prophaethon from the early Eocene of England. (In fact, Lithoptila is the oldest crown bird known from Africa.) The placement of both these genera as stem-tropicbirds has been supported by phylogenetic analyses, though results differ on whether they form a clade with one another that excludes crown tropicbirds (Bourdon et al., 2005; Smith, 2010).

Lithoptila and Prophaethon were around the same size as extant tropicbirds, but had a longer pelvis and longer feet, suggesting that they were more capable swimmers. Although they were probably strong fliers, details of their wing skeleton indicate that they may not have been aerial specialists the way modern tropicbirds are. It has been proposed that Prophaethon lacked the elongate tail feathers of its closest living relatives, based on the shorter transverse processes (sideways projections) on its tail vertebrae (Mayr, 2015). The abundance of remains known from Lithoptila and Prophaethon suggest that they approached continental shorelines more frequently than extant tropicbirds do, maybe even forming large breeding colonies in these habitats (Bourdon et al., 2008a; Mayr, 2015). Taken together, these lines of evidence paint these stem-tropicbirds as having been less pelagic than modern tropicbirds, but potentially having spent more of their time in the water. Mayr (2015) speculated that they caught prey while swimming on the water's surface, similar to albatrosses. The aquatic inclinations of stem-tropicbirds may provide a plausible explanation for why extant tropicbirds retain totipalmate feet.

The foot of Prophaethon (a) compared to that of a white-tailed tropicbird (b), from Mayr (2015). The scale bars = 5 mm; as can be seen, Prophaethon had a much longer foot than modern tropicbirds, despite being similar in body size.

Another early stem-tropicbird was Zhylgaia, known from partial humeri dating to the late Paleocene of Kazakhstan that were originally mistaken for those of a shorebird (Bourdon et al., 2008a). Mayr and Scofield (2016) further noted that a tarsometatarsus (fused ankle and foot bones) described as "Tshulia" from the same time and place probably belongs to Zhylgaia. Other possible stem-tropicbird specimens similar to Lithoptila and Prophaethon have been reported from the late Paleocene of the eastern United States (Olson, 1994) and the middle Eocene of Belgium (Mayr and Smith, 2002). Additionally, the supposed ibis "Proplegadis", known from a fragmentary humerus from the Eocene of England, is likely a specimen of Prophaethon (Mayr, 2015).

Possibly more closely related to extant tropicbirds was Phaethusavis from the early Eocene of Morocco, based on a partial humerus (Bourdon et al., 2008b). After the Eocene, the completeness of the tropicbird fossil record appears to drop off sharply, perhaps corresponding to the onset of more pelagic tendencies. Nonetheless, there are a few younger fossil tropicbirds that have been described from regions where tropicbirds no longer occur, such as Heliadornis ashbyi from the middle Miocene of Belgium and the eastern United States (Olson, 1985; Olson and Walker, 1997), as well as possibly Heliadornis paratethydicus from the late Miocene of Austria (Mlíkovský, 1997) and Heliadornis minor from the late Pliocene of Slovakia (Kessler, 2009).

Why tropicbirds vanished from higher latitudes is unknown. Mayr (2015) suggested that competition and predation from other organisms may have driven them to specialize in living off nutrient-poor tropical waters, where food sources are relatively patchy and scarce. The Neogene disappearance of tropicbirds from high latitudes and their current restriction to the tropics bring to mind similar biogeographic histories in some terrestrial bird groups (such as mousebirds), which have been attributed to global climate change. It makes me wonder whether tropicbirds represent a marine example of this recurrent pattern.

One of the most longstanding mysteries surrounding the evolutionary history of tropicbirds concerns their phylogenetic position. Traditionally, tropicbirds were grouped together as "pelecaniforms" alongside pelicans, frigatebirds, boobies, cormorants, and anhingas, with which they share totipalmate feet. Tropicbirds have long been recognized as the "odd ones out" in this collective, however. For example, they lack a bare throat pouch, a long hallux (innermost toe), or reduced external nostrils, and have a covering of downy feathers upon hatching (as opposed to being naked). Some researchers instead argued for a closer relationship between tropicbirds and procellariiform birds (albatrosses, petrels, and kin), which was supported by several phylogenetic analyses based on morphological characteristics (Mayr, 2003; Bourdon et al., 2005; Smith, 2010).

Red-tailed tropicbird chick, covered in fluffy down, photographed by Forest & Kim Starr, under CC BY 3.0.

The rise of large-scale molecular phylogenetic analyses has greatly clarified the relationships among modern bird groups, and one of their major findings has led to the breakup of the traditional "pelecaniforms". It turns out that though frigatebirds, boobies, cormorants, and anhingas do form a clade (now known as Suliformes), pelicans are more closely related to herons, ibises, shoebills, and hamerkops, with the name Pelecaniformes now applied to this latter assemblage. Both suliforms and pelecaniforms, however, belong to a large group of mostly aquatic birds called Aequornithes, which also contains storks, procellariiforms, penguins, and loons.

A surprising commonality among the results of these analyses was that tropicbirds were not found as members of Aequornithes, meaning that they are not especially closely related to pelecaniforms, suliforms, or procellariiforms. However, early molecular phylogenetic analyses found little consistent support for what tropicbirds actually are closely related to. It was only more recently with the advent of increasingly large datasets that a more widely corroborated answer to that question has emerged, and it is an unexpected one: the closest living relatives of tropicbirds are likely the eurypygiforms.

... Well, it might be hard to find that shocking if one is not familiar with eurypygiforms. They are a group of birds that includes just two living species: the heron-like sunbittern (Eurypyga helias) from the Neotropics and the nearly flightless kagu (Rhynochetos jubatus) from New Caledonia, both of which exhibit little if any obvious anatomical similarity with tropicbirds. Furthermore, though the sunbittern regularly forages for prey in freshwater environments, neither species shows any inclination towards a marine lifestyle.

A sunbittern, which does not look or behave a whole lot like a tropicbird, photographed by Brent Moore, under CC BY 2.0.

Yet time and time again, a close relationship between tropicbirds and eurypygiforms (first recovered by McCormack et al., 2013) has been supported by recent large-scale analyses of genetic data (Jarvis et al., 2014; Prum et al., 2015; Reddy et al., 2017; Kuhl et al., 2021). Most (though not all) of these studies also place the eurypygiform–tropicbird clade (which has been called Phaethontimorphae) as most closely related to Aequornithes, forming an expanded "waterbird clade". (At present, no formal name has been assigned to the group uniting phaethontimorphs and aequornitheans in technical literature, though John Boyd has adopted the old name Ardeae for this clade on his Taxonomy in Flux website. Personally, I think another old name, Natatores, would also be a reasonable option, as it has been applied to a very similar assemblage of birds in at least one 21st Century paper.)

The current consensus of phylogenetic relationships in the expanded "waterbird clade", plotted against geologic time.

The eurypygiform–tropicbird relationship has not gone ignored in paleontological studies. Despite this, essentially no anatomical features that clearly characterize this clade have been identified, and even the existence of well-represented stem-tropicbird fossils has so far been of limited help in this regard (Mayr, 2014; Mayr, 2019). If anything, the aquatic adaptations of stem-tropicbirds seem to render the the close relationship with the terrestrial eurypygiforms even more baffling. Prophaethon does share with eurypygiforms long, slit-like nostril openings in the skull (which are retained in extant tropicbirds only as juveniles), but this feature is also found in most aequornitheans (Mayr, 2014). 

Skulls of Prophaethon (A), a red-tailed tropicbird (B), a juvenile brown pelican (C,  Pelecanus occidentalis), and a sunbittern (D), from Mayr (2014). Arrows indicate the extent of bony nostril openings.

Perhaps the biggest missing piece of the puzzle though is the virtual absence of known fossil eurypygiform specimens. There is a fossil from the Eocene Green River Formation of the western United States that has been proposed to be a stem-sunbittern; however, it has not yet been formally described. A group of Paleogene birds called the messelornithids were originally suggested to have been eurypygiforms, but all recent studies on their phylogenetic affinities instead find that they were probably gruiform birds, more closely related to cranes and rails.

So maybe the discovery of unambiguous stem-eurypygiforms will further clarify the evolutionary connection between eurypygiforms and tropicbirds. Such fossils may also have the potential to shed light on other aspects of tropicbird evolution, like whether their marine ecology was inherited from the last common ancestor of the expanded "waterbird clade" or arose independently in total-group tropicbirds and aequornitheans.

For now, there is clearly much we have yet to learn about tropicbirds. None of the three extant species are considered to be under immediate threat of extinction, though many of their breeding grounds are at risk from introduced predators, and their pelagic habits make their population trends difficult to monitor. However, if effective conservation measures are established and maintained, it is likely that we will have the opportunity to marvel at these angels of the high seas long into the foreseeable future.

White-tailed tropicbird in flight, photographed by hokoonwong, under CC BY-NC 4.0. Fly on, mysterious angel.


Thursday, April 1, 2021

Songs About the Fossil Record

It's annual off-topic day on this blog! What should I talk about? How about... music?

My taste in music is, shall we say... idiosyncratic. I don't tend to consciously gravitate towards specific genres in terms of musical styles, and I can't tell you anything about what songs are popular right now—chances are that I probably haven't even heard of those songs before, unless they've somehow become universal internet memes. However, I do have an affinity for songs about specific subjects, namely songs about science, and especially songs about the branches of science that I'm most interested in, like zoology and paleontology.

If that isn't a niche preference in music, I don't know what is. What's the appeal, anyway? In part, it might be that I often find music to be a very effective tool for learning. Many concepts become more memorable once you can associate them with a catchy tune. More than that, however, I think it's wonderful to see (or, perhaps more accurately in this context, hear) someone take seemingly arcane topics and turn them into an art form that can potentially connect with people who might otherwise have never heard of those subjects.

Well, I suppose the key word there is "potentially", because most people will probably be surprised to hear that songs about paleontology exist at all. Yet exist they do, and there are even some written by bands that would probably be considered mainstream. "History of Everything" (better known as the theme song to The Big Bang Theory*) by the Barenaked Ladies and "Endless Forms Most Beautiful" by Nightwish both take clear inspiration from paleontological concepts.

*I'm not a fan of the show. I still think it's a great song though.

Probably the song that is most famously associated with the field of paleontology, however, is "I am a Paleontologist" by They Might Be Giants (TMBG), which is embedded below. It is a longstanding tradition for attendees of the annual Society of Vertebrate Paleontology (SVP) conference to dance along to this song multiple times during the conference afterparty.

Yet even within the paleontology community, it sometimes appears that "I am a Paleontologist" is one of the few songs about paleontology that most people are familiar with, which I'm ever so slightly vexed by. Don't get me wrong, I love TMBG. (They even wrote my favorite song of all time, which ironically isn't a song about science, though I've unabashedly reinterpreted it as one.) However, there are more than enough songs about paleontology out there to make entire SVP afterparty playlists out of, so I find it somewhat disappointing that this is not capitalized on more often during what are some of the most appropriate possible events for these songs to be played at. And that is, in part, the impetus for this post.

This will not be a complete list of paleontology-related songs by any means. Believe it or not, there are too many for me to easily cover in a single post, and I regularly discover examples that I had been previously unaware of. Consider this a selected highlights reel, if you will.

I can start off with the fact that TMBG actually has at least a couple of lesser-known paleontology-adjacent songs, most notably "Mammal", which has a verse describing the phylogenetic relationships among major mammal lineages, and even mentions allotherians! A funny aside that is worth bringing up here is that TMBG's bassist Danny Weinkauf (who was also the lead singer on "I am a Paleontologist") wrote the song "Archaeology" apparently because audiences kept mistaking "I am a Paleontologist" for an "archaeology song".

Paleontology-inspired songs have a surprisingly long history. A song or poem about extinct dinosaurs was written by Edward Forbes for the famous 1853 New Year's Eve banquet that was held inside the clay mold of one of the Crystal Palace Iguanodon models. The original tune of the ditty (if it had one) is unknown, but Barney Brown, head of digital communications at the University of Cambridge, has set the words to music.

I don't know what the oldest paleontology-inspired song with a surviving tune is, but "It's a Long Way From Amphioxus" (sung to the tune of "It's a Long Way to Tipperary") is probably the oldest that I'm personally aware of. According to Joe Felsenstein's extremely informative website about this song, it had its chorus written by an unknown author sometime between 1912 and 1921, with additional verses penned by Philip H. Pope in 1921. Embedded below is a particularly well-known rendition of it performed by Sam Hinton. Although the science is outdated and the final verse is perhaps too blatantly obvious about written by a vertebrate, it's not hard to see why this song is such a classic.

In the late 1980s and through the 1990s, several paleontology-themed albums were released by James Robinson. Though he is no longer active in academia, Robinson was a working paleontologist for some time, notably authoring a key 1975 paper on whether plesiosaurs moved by drag-based swimming (rowing) or lift-based swimming (underwater flight). This subject naturally became the basis for one of his tunes, "Plesiosaurnithology". Listening to Robinson's songs, it is evident that they were written by someone with an insider's perspective on paleontology. "Ambition" is about the dinosaurian origin of birds (this in the 80s!) and "Systematic Classification" has a verse about how paleobotanists often coin different names for each part of the same plant. Although it's not specific to paleontology, I'd also like to mention "Anthem to Bureaucracy", which is still very salient in current times.

Most of Robinson's songs have been uploaded to YouTube as entire albums, so embedding them here probably would not be the most effective way to showcase individual tracks. Have a picture of "flying" plesiosaur instead, photographed by Kim Alaniz, under CC BY 2.0.

Paleontology-inspired music remains alive and well today, and there are even artists who specialize in producing it. Ray Troll is well known in the paleontology community for his surreal paleoart, but he is also a musician who performs as part of the band The Ratfish Wranglers, and many of their songs are appropriately paleontology-based. If I had to pick a favorite, it would probably be "Cruisin' the Fossil Freeway" (embedded below), which I think nicely encapsulates the spirit of paleontological discovery. (The song is named after the book of the same name authored by Kirk Johnson and illustrated by Troll.) I also greatly enjoy "Whorl Tooth Sharks of Idaho", about the recent reinterpretation of the bizarre stem-ratfish Helicoprion, and "Snowmastodon", about the Snowmastodon fossil site. An amusing anecdote I have is that "Snowmastodon" was where I first heard the name of paleobotanist Ian Miller, who had a good laugh when I told him this at SVP 2019.

Another paleontology-focused musician is Professor Flint, whose work has at least received some recognition from SVP, as he put on a live performance at SVP 2019. Professor Flint specializes in songs about Australian fossils in particular, and has produced tunes about taxa as obscure as the giant Pleistocene cuckoo Centropus maximus and the Pleistocene stem-koala Invictokoala (the latter co-written by Gilbert Price, one of the describers of Invictokoala). My personal favorite though is probably "Gigantic, Enormous, Ginormous, Genyornis" (embedded below). His tribute to Mary Anning is also quite delightful.

Then there are the The Amoeba People, whose songs celebrate a wide range of geosciences. In fact, my favorite song of theirs is "Girl Talk", which is not about paleontology, but the scientific contributions of oceanographic cartographer Marie Tharp and the struggles she faced as a woman in science. The Amoeba People haven't neglected paleontology in their output, however, with entries like "The Ballad of Barnum Brown" (embedded below) and "The Terrible Lizards". (And yes, every genus mentioned in the latter song, with the possible exception of Saltopus, is actually a dinosaur.)

Some music artists cover a remarkable diversity of scientific topics in their work. John Hinton has written songs about just about every major field of science there is for his Ensonglopedia series of shows. Although he hasn't yet produced an Ensonglopedia of Palaeontology (or Geoscience), he has touched on paleontology more than once with "The Jurassic Jive" from Ensonglopedia of Science, as well as "D is for Dunkleosteus" (embedded below), "I is for Ice Age", and "J is for Jehol Biota" from his ongoing online song challenge series. (Full disclosure: I was a scientific consultant on those last three songs.)

My own favorite of Hinton's works though is Ensonglopedia of Animals, and there's a lot there for paleontologists to appreciate. Although all the songs are about extant animal species (except maybe the Togo red jewel damselfly, which hasn't been recorded since its original description in 1898), phylogeny and evolutionary history are given a lot of focus. For example, "Aye-Aye" starts out with an overview of primate evolution, "Narwhal" highlights the fact that whales are ungulates, and "Verreaux's Eagle" mentions that birds are dinosaurs. In fact, the very structure of the show is based on phylogenetic relationships, starting with a song about humans and ending with one about sponges, our most distant relatives among animals. I was so impressed by Ensonglopedia of Animals that I was inspired to draw fan art of it.

This post is getting long, so I'm going to end this with a lightning round of select songs from various artists. "Dinosaurs" by Biscuithead and the Biscuit Badgers (embedded below) is a perfect summation of why people love dinosaurs. "Tiktaalik (Your Inner Fish)" by The Indoorfins is a great celebration of that stem-tetrapod and, in my experience, is actually fairly well-known in the paleontology community. (The Indoorfins also did "Amphibian Ark", a nice tune about amphibian conservation.) "Cambrian Explosion" and "Silurian" by Brighter Lights, Thicker Glasses are lovely tributes to those early periods in Phanerozoic history. "Quetzalcoatlus" by David Cagle really gets across how spectacular that giant pterosaur must have been. "How We Met, The Long Version" by Jens Lekman cleverly turns the origin of the universe (and eventually humankind) into a love song.

As eccentric as my musical tastes may be, I am not the first in the paleoblogosphere to write at length about paleontology songs. Andrew Stück of Dino Dad Reviews has covered the subject several times, with posts dedicated to The Ratfish Wranglers, Professor Flint, The Amoeba People, and more. Maybe when in-person gatherings are a thing again, some of the songs mentioned in these posts will finally get the attention they deserve at conference afterparties.

Tuesday, January 19, 2021

New (Extinct) Maniraptors of 2020

The "new year" is not so new anymore (three new maniraptors have been named in 2021 already), but this is a tradition and I'm sticking to it, for now. Having done a sweeping overview of the past year in maniraptoran discoveries, I will now take a more in-depth look at the new extinct taxa that were described last year. In addition to the new genera and species of 2020, this time around I will also make an effort to mention other relevant nomenclatural changes that were proposed.

Last year saw the naming of Trierarchuncus, the youngest known alvarezsaur. Fragmentary alvarezsaur specimens had been previously reported from the latest Cretaceous Hell Creek and Lance Formations of the western United States, but these fossils had been left unnamed. Trierarchuncus itself is not known from a whole lot—it was described based on three thumb claws (belonging to three different individuals) from the Hell Creek Formation, and there are parts of an arm and a foot as well as a previously described partial hip that may also belong to it. Shortly after its initial description, a second paper assigned two more thumb claws to Trierarchuncus.

Even though the specimens don't represent much of the skeleton, Trierarchuncus is potentially quite informative about alvarezsaur biology. I noted last year in a post about alvarezsaurids that completely preserved alvarezsaurid thumb claws are rare. One of the claws assigned to Trierarchuncus, however, is very complete, showing a sharp tip and stronger curvature than is typically assumed for alvarezsaurid thumb claws. To my eye at least, this claw shape is in keeping with use of the claw in hook-and-pull digging, as I had contended in my blog post (and others had contended in scientific papers). Perhaps in reference to the strongly curved claw, the name Trierarchuncus can be translated as "Captain Hook".

The most completely preserved thumb claw referred to Trierarchuncus, from Fowler et al. (2020).

Seeing as the claws assigned to Trierarchuncus come from individuals of different sizes, they may also provide insight into how alvarezsaurid claws changed as they grew. The larger Trierarchuncus claws are widened at their base and the surface of the bone exhibits a roughened texture, which likely developed as a response to considerable stresses. The authors who made these observations noted that this is also consistent with the hypothesis that alvarezsaurids used their thumb claws for digging.

One of the most spectacular new maniraptors from last year, in terms of the fossil material represented, may have been the oviraptorid Oksoko from the Late Cretaceous Nemegt Formation of Mongolia. It is known from the skeletons of several individuals, including nearly complete skeletons. Notably among these specimens is an assemblage of at least three (maybe four) juveniles preserved together, which had been confiscated from fossil poachers in 2006. Some of these juveniles are preserved in lifelike crouched postures, suggesting that they had been buried rapidly and simultaneously. They therefore provide strong evidence of gregarious behavior in oviraptorosaurs. Oksoko was unusual among oviraptorosaurs in that its third finger was highly reduced, giving it functionally two-fingered hands, and the describers note that similar hands may have been present in Heyuannia huangi.

Several juvenile specimens of Oksoko (including the holotype, marked in blue) preserved together, from Funston et al. (2020).

2020 also saw a much-needed taxonomic overhaul of the caenagnathid oviraptorosaurs from the Late Cretaceous Dinosaur Park Formation in Alberta. Many Dinosaur Park caenagnathids were named based on non-overlapping parts of the skeleton, which has naturally raised questions about whether they all really represent distinct species or not. Based on the examination of newly described, more complete specimens, as well as assessment of individual growth stage based on bone microstructure, this latest study concluded that there are probably three distinct caenagnathids known from the Dinosaur Park Formation: the large Caenagnathus, the medium-sized Chirostenotes, and the small, newly-named genus Citipes, which had formerly often been considered a species of either Chirostenotes or Leptorhynchos. Although not the main focus of the study, this paper additionally mentions that the Gobiraptor from the Nemegt Formation likely represents a juvenile of Conchoraptor, as had been hinted in the past.

Also in the world of oviraptorosaur taxonomy, the feather-preserving specimens of Similicaudipteryx were reassigned to Incisivosaurus (previously known only from a skull and partial neck vertebra).

Non-ornithothoracean Paravians
In contrast to 2019, which was conspicuously lacking in new dromaeosaurids, at least two new dromaeosaurids were described in 2020. One of these was the microraptorian Wulong from the Early Cretaceous Jiufotang Formation of China, known from the exquisitely-preserved complete skeleton of an immature individual. Like Microraptor, Wulong had large feathers on its hindlimbs, and the specimen also preserves a single pair of elongated tail feathers at the tip of its tail.

Holotype of Wulong, from Poust et al. (2020).

The other new dromaeosaurid was Dineobellator, a mid-sized (Velociraptor-sized) dromaeosaurid from the Late Cretaceous Ojo Alamo Formation of the United States. It is known from a partial skeleton, and as in Velociraptor and Dakotaraptor, its ulna exhibits a series of bumps for the attachment of wing feathers along the forearm.

One new paravian that might be a dromaeosaurid was Overoraptor, known from a couple of partial skeletons from the Late Cretaceous Huincul Formation of Argentina. The phylogenetic analysis in the description of Overoraptor recovered it as a close relative of Rahonavis, a smaller, likely flight-capable paravian from the Late Cretaceous of Madagascar. The phylogenetic position of Rahonavis is controversial; it has been found as either an unenlagiine dromaeosaurid or an avialan in recent studies. This particular study found Overoraptor and Rahonavis as avialans, though the phylogenetic dataset used tends to find paravian relationships that are not strongly supported by other analyses, with microraptorians and unenlagiines outside of dromaeosaurids and instead being more closely related to modern birds. It would be interesting to see where Overoraptor turns up when included in other phylogenetic datasets.

Rounding out the long-tailed paravians of 2020 is Kompsornis, a Jeholornis-like avialan from the Jiufotang Formation. The taxonomy of the various Jeholornis-like avialans is debated, but the describers of Kompsornis argue that Shenzhouraptor, Jixiangornis, Jeholornis prima, Jeholornis palmapenis, and Jeholornis curvipes all represent distinct, valid taxa. This paper is also notably one of the few to address "Dalianraptor", a supposedly short-armed, long-tailed avialan. The authors confirm that the original specimen of "Dalianraptor" is likely a composite, and find no definitive features that distinguish it from other Jeholornis-like avialans.

Only one new enantiornithean was named last year, but it was a doozy. Falcatakely from the Late Cretaceous Maevarano Formation of Madagascar is known from a nearly complete skull, and it's a skull unlike that of any other known theropod. Its snout was long and tall, giving it a superficial resemblance to a toucan or a hornbill. However, most of the snout was composed of enlarged maxilla bones, contrasting with the condition in modern birds, in which the snout is primarily composed of the premaxillae. The maxillae of Falcatakely were toothless and probably covered in a keratinous sheath, but the specimen preserves at least one small premaxillary tooth.

Holotype of Falcatakely, from O'Connor et al. (2020).

The describers of Falcatakely ran several different phylogenetic analyses and consistently recovered it as an enantiornithean each time. Even so, it's probably fair to wonder whether this bizarre creature really was an enantiornithean, especially considering that very few other Late Cretaceous enantiornithean skulls are known for comparison. As Mickey Mortimer has pointed out, a highly modified Late Cretaceous theropod with no obvious close relatives and known from limited remains is likely going to be difficult to place no matter what. (It's perhaps worthy of note that little to no skull material has been found for the two other paravians that have been named from the Maevarano Formation, Rahonavis and Vorona.) Regardless of what it turns out to be, the unusual and unexpected morphology of Falcatakely easily qualifies it as one of the highlights among last year's new dinosaurs.

In other news, a review of the Mesozoic and Paleocene pennaraptoran fossil record considered the poorly-studied Jiufotang enantiornitheans Largirostrornis and Longchengornis to be synonyms of Cathayornis, though this was not elaborated upon.

Non-neornithean Euornitheans
The taxonomy of yanornithid euornitheans was revised in 2020, resulting in the recognition of two new genera, Abitusavis and Similiyanornis. Similiyanornis from the Jiufotang Formation had a distinctive tooth arrangement in which the frontmost tooth in its lower jaw was enlarged. Abitusavis was larger than Similiyanornis and was discovered in the older Yixian Formation. Of note is that the first yanornithid specimen reported with fish remains preserved in its digestive tract (originally assigned to Yanornis) is now considered a specimen of Abitusavis. Several other previously described specimens (including the poorly-studied "Aberratiodontus") were deemed indeterminate yanornithids in this study, whereas Yanornis guozhangi was sunk into the type species of Yanornis, Y. martini.

Holotype of Similiyanornis, from Wang et al. (2020).

Another new Early Cretaceous euornithean is Khinganornis from the Longjiang Formation of China. It is the first dinosaur to be described from this formation, and is known from a nearly complete skeleton, but its anatomical details are not well preserved. It appears to have been generally similar to the semi-aquatic euornitheans Gansus and Iteravis, and may have led a similar lifestyle.

No new paleognaths were named last year (at least, none based on skeletal material), but the old genus Palaeostruthio was brought back and applied to "Struthio" karatheodoris, a large ostrich from the Miocene of Eurasia.

Alright, let's do this one more time... Asteriornis from the Late Cretaceous Maastricht Formation of Western Europe is one of the few well-established examples of a Mesozoic crown bird. It is known from several bones, most notably a nearly complete skull. The skull exhibits features characteristic of both anseriforms and galliforms, and Asterornis may thus be a close approximation of what the ancestral galloanseran looked like. There's plenty more that could be said, but I already wrote about Asteriornis in more detail here.

Skull of Asteriornis, from Field et al. (2020).

The Cenozoic contributed its fair share of new galloanserans as well. From the Eocene of Kazakhstan came the anseriform Cousteauvia, known from a tarsometatarsus that displays features suggestive of diving behavior (hence the name honoring Jacques Cousteau). Its full binomial, Cousteauvia kustovia, is a bit of fun with homophones. There were also a couple of new pheasants from Bulgaria, the Miocene Phasianus bulgaricus and the Pleistocene Chauvireria bulgarica.

It's not often that we get a new gastornithid, but last year gave us Gastornis laurenti from the Eocene of France. It was named based on a distinctive lower jaw, but its describers mention that it is known from postcranial bones as well, which will be described in a later publication.

What's this? A fossil columbimorph older than the Pleistocene and represented by decently complete material?! Linxiavis was a sandgrouse from the Miocene Liushu Formation of China, and is known from a partial skeleton including most of the forelimbs. Sandgrouse today live in arid habitats (they famously use their belly feathers to transport water for their young), so the discovery of Linxiavis is consistent with other lines of evidence suggesting that the Liushu Formation was deposited in a relatively dry environment.

Holotype of Linxiavis, from Li et al. (2020).

A new columbimorph that lived in more recent times is the Pleistocene–Holocene pigeon Tongoenas, remains of which are known from several islands in the Kingdom of Tonga. Its hindlimb anatomy suggests that it was a primarily tree-dwelling form, similar to the fruit doves and imperial pigeons that are still extant today. Tongoenas was one of the largest known flying pigeons, surpassed in that department only by the crowned pigeons, which can reach the size of a small turkey.

The one new gruiform named last year was the coot Fulica montanei, known from a few tarsometatarsi found in the Pleistocene–Holocene Laguna de Tagua Tagua Formation of Chile. It was large for a coot, comparable in size to the extant horned coot (F. cornuta), and potentially had limited flight capabilities due to its size.

Meanwhile, to maintain consistency with the current taxonomy of extant cranes, the Pleistocene Cuban flightless crane "Grus" cubensis was transferred to the genus Antigone, which includes its probable close relatives such as the sarus (A. antigone) and sandhill (A. canadensis) cranes.

The origins of charadriiforms are murky, but 2020 saw the publication of a new taxon that may bear on the subject. That new taxon was Nahmavis from the Eocene Green River Formation of the United States, and it is known from a partial skeleton (missing the forelimbs and shoulder girdle) with preserved feathers. This specimen had previously been reported in popular books and websites as a potential close relative of the seriema-like bird Salmila from the Eocene of Germany, but the describers of Nahmavis instead find it to be more similar to possible stem-charadriiform Scandiavis from the Eocene of Denmark.

In the new study, Nahmavis and Scandiavis were indeed sometimes found as stem-charadriiforms. However, other analyses in this paper placed them as gruiforms instead. It is unfortunate that forelimb material is unknown for both Nahmavis and Scandiavis, seeing as the forelimb bones of charadriiforms are often distinctive. For what it's worth, playing around with the phylogenetic dataset used in this study, I've found that Nahmavis and Scandiavis are consistently recovered as stem-charadriiforms when the internal topology of crown charadriiforms is constrained to the results of molecular studies. In any case, the holotype of Nahmavis is a lovely specimen, and it's good to see it described at last.

Holotype of Nahmavis, from Musser and Clarke (2020).

Among crown charadriiforms, a new species described last year was the recently extinct sandpiper Prosobonia sauli from Henderson Island in the Pitcairn Islands. The genus Prosobonia also includes at least three other extinct sandpiper species as well as the extant Tuamotu sandpiper (P. parvirostris). Unlike typical sandpipers, the members of this genus are not migratory, and are confined to various remote Polynesian islands. Compared to the Tuamotu sandpiper, P. sauli had a wider, straighter bill tip and longer hindlimbs.

As yet, it appears that no one has formally suggested in technical literature what name should be used for the clade uniting phaethontimorphs (tropicbirds, sunbitterns, and kagus) and aequornitheans ("core waterbirds", such as penguins, petrels, pelicans, etc.). I have provisionally settled on resurrecting the old name Natatores for this group, as it has been used in relatively recent literature for a very similar assemblage of birds.

Fossil penguins have generally had a good showing in recent years, and 2020 added Eudyptes atatu from the Pliocene Tangahoe Formation of New Zealand to the lineup. It is known from several specimens, and the holotype is a partial skeleton that includes much of the skull and shoulder girdle. E. atatu was closely related to the extant crested penguins, but its beak was shallower in depth compared to the fairly tall beak seen in the living members of this genus.

Two other new natatoreans belonged to a different group of wing-propelled divers, the extinct plotopterids, which were probably close relatives of boobies and cormorants. The new plotopterids Empeirodytes and Stenornis both come from the Oligocene of Japan and are known from isolated coracoids, with Stenornis being the larger of the two.

Whereas no raptorial telluravians were named in 2019, 2020 turned out to be extremely productive in the realm of new raptors. Two New World vultures were named from the Quaternary of Cuba, Coragyps seductus (which was similar to the extant black vulture, Coragyps atratus) and Cathartes emsliei (the smallest member of the genus Cathartes, which also includes the turkey vulture, C. aura, among others).

The Quaternary of Cuba gave us three new hawk species as well, these being Gigantohierax itchei, Buteogallus royi, and Buteo sanfelipensis. G. itchei was the biggest of the three (though it wasn't as big as the type species of Gigantohierax, G. suarezi), whereas B. sanfelipensis was the smallest, being somewhat smaller than a red-tailed hawk (Buteo jamaicensis). From further back in geologic time, we got the large Vinchinavis from the Miocene Toro Negro Formation of Argentina, represented by partial forearm bones. Even older was ?Palaeoplancus dammanni from the Eocene of the United States, known from a tarsometatarsus.

Arguably the most spectacular new accipitrid, however, was Aviraptor from the Oligocene of Poland. It wasn't spectacular due to its size—it was the smallest of the new accipitrids, about the same size as the aptly-named tiny hawk (Accipiter superciliosus). However, it is known from a nearly complete skeleton, a rarity among fossil accipitrids. Its combination of small body size and relatively long hindlimbs is commonly seen in extant accipitrids that hunt other birds, suggesting that it may have had similar habits. It may not be a coincidence that early hummingbirds and passeriforms are known to have lived in Europe at around the same time as Aviraptor.

Holotype of Aviraptor, from Mayr and Hurum (2020).

The surge of new fossil raptors was not limited to vultures and hawks, as fossil owls had a very good year, too. There was the pygmy owl Glaucidium ireneae from the Pliocene–Pleistocene of South Africa, the oldest unambiguous member of its genus from Africa. The Quaternary of Cuba contributed the small barn owl Tyto maniola and the giant Ornimegalonyx ewingi, the latter based on specimens previously assigned to the horned owl Bubo osvaldoi. Although O. ewingi was much smaller than the type species of Ornimegalonyx, O. oteroi, it was still larger than any living owl species. The remaining species of Ornimegalonyx (O. acevedoi, O. gigas, and O. minor), however, have been sunk into O. oteroi.

Another large owl was Asio ecuadoriensis from the Pleistocene Cangagua Formation of Ecuador. Known from a couple of robust hindlimb bones, it was about the same size as a great horned owl (Bubo virginianus). Interestingly, its remains were found in association with the bones of smaller owls (and small mammals) that appear to have been etched by stomach acid, suggesting that it may have preyed on other owl species.

Numerous owls have been named from Paleogene fossil deposits, but most of these species are based on very limited material. Primoptynx from the Eocene Willwood Formation of the United States is known from a partial skeleton, making it one of the most completely known Paleogene owls. Like accipitrids, but unlike extant owls, Primoptynx had enlarged claws on its first and second toes, perhaps implying that it captured prey in a similar manner to accipitrids (maybe making use of the infamous "raptor prey restraint" method that may have also been employed by dromaeosaurids).

Toes of Primoptynx, from Mayr et al. (2020). The claws on the first and second toes are particularly large.

Moving away from raptors for a moment, Jacamatia from the Oligocene of France was a tiny piciform known from a partial wing skeleton. Its describers suggest that it was closely related to the jacamars and puffbirds, which are otherwise poorly represented in the fossil record. It may have belonged to the Sylphornithidae, a group of similarly tiny Paleogene piciforms, though very little overlapping material is available for comparison.

On the australavian side of Telluraves, we meet the small caracara Milvago diazfrancoi, yet another new raptor from the Quaternary of Cuba. The remaining new fossil australavians of 2020 were all songbirds: the corvid Corvus bragai from the Pliocene–Pleistocene of South Africa (the oldest known corvid from Africa) and the New World blackbirds Icterus turmalis and Molothrus resinosus from the Pleistocene Talara tar seeps of Peru.

Some additional revisions of note concerning fossil songbirds: the holotype of "Pliocalcarius" from the Pliocene of Central Asia, originally described as a longspur, was reinterpreted as a lark and transferred to the horned lark genus Eremophila, whereas "Eremophila" prealpestris from the Pleistocene of Bulgaria was argued to have been more similar to a different lark genus, Ammomanes, and removed from Eremophila.

Friday, January 1, 2021

Review of 2020

Wow, a record low in annual post count for this blog. It hasn't been for a lack of topics to write about; I had wanted to blog about estimating neoavian divergence times, the fossil record of shorebirds, the many origins of flightlessness in waterfowl, and more, but I never got around to doing so. Time will tell if I ever do. In part, I've been inactive here because I've been busy. The pandemic hasn't slowed down my academic activities much (for which I'm thankful), so I've still had my hands full working on research projects, reviewing manuscripts, and attending conferences. Those conferences went well for most part, but the switch to online formats meant that I felt less motivated to blog about them, further contributing to the lack of activity here. (Although come to think of it, a post about how online and in-person conference experiences differ might have been interesting...) I also wasn't able to make any new trips to zoos or museums, so there weren't any posts about those either.

My neglect of the blog notwithstanding, I did find the opportunity to work on a few other non-academic projects in 2020. In June, I helped put together the Dino Nerds for Black Lives livestream, and even now I'm flabbergasted that we managed to pull it off. For those who missed or would like to re-experience the livestream, most of the segments have been made available online. In addition to organizing and hosting parts of the event, I also presented a segment on the stream with my longtime friend and collaborator Joan Turmelle, in which we did a one-time revival of our old radio show Incidents and Reflections

Joan and I enjoyed doing the radio show again, so we later started a new podcast, Through Time and Clades. Strictly speaking, our show also includes visual aids, so it's not quite a conventional podcast. We currently operate on a rotating schedule. For the first episode of every month, we discuss a selection of notable new studies on natural history that came out during the previous month. Following that, we switch back and forth each week between two different series until the next month rolls around. One series, led by Joan, discusses human origins, whereas the other series, led by me, discusses the diversity and evolution of crown-group birds (and thus might be of particular interest to readers of this blog).

The title slide for the first episode of "Dinosaurs, the Second Chapter", my podcast series on crown bird evolution.

Possibly the most exciting personal achievement for me in 2020, however, was the fact that I helped name a new dinosaur in Nature! That dinosaur was Asteriornis maastrichtensis, one of the few clear examples of a Cretaceous crown bird, and the holotype includes one of the best-preserved fossil bird skulls yet found. As I wrote about previously, the discovery of this new species was highly serendipitous, and I don't expect that I'll have the chance to take part in such a high-profile study again anytime soon.

Skull of the holotype of Asteriornis maastrichtensis, from Field et al. (2020).

The description of Asteriornis might have been my favorite study from last year (if I may say so myself), but it was far from alone. Despite the state of the world, plenty of new maniraptoran research continued to be published throughout 2020, so let's take a look. As always, my coverage of papers about modern birds is necessarily going to be incomplete, so I put more focus on those that have more direct connections to paleontology, such as studies on anatomy, ontogeny, and higher-order phylogeny.

In January, African gray parrots were reported to voluntarily help members of their own species obtain food rewards. Eggshells from the Late Cretaceous of Europe thought to belong to geckos were reinterpreted as maniraptoran in origin. Avian paleoneurology was reviewed. Seabirds from the Pleistocene of Japan, birds from the Eocene of Antarctica, a partial skeleton of a Paleocene penguin, preserved skin in Palaeeudyptes, and the vocal tract anatomy of king penguins were described. Reversible outer toes were reported in gray-headed and lesser fish eagles. Red-breasted nuthatches were shown to vary their alarm calls according to eavesdropped signals from other birds. New studies came out on how flight feathers stick to one another, the brain structure of extinct avialans, convergent evolution in birds, pelvic ontogeny in greater rheas, life history changes in birds from the La Brea tar pits, the evolution of melanosomes in hummingbirds, evolutionary rates in passeriforms, evolutionary drivers in Acanthiza thornbills, and the phylogeny of Turdus thrushes. Newly-named maniraptors included the microraptorian dromaeosaurid Wulong bohaiensis, the Taliabu myzomela (Myzomela wahe), the Peleng fantail (Rhipidura habibiei), the Taliabu grasshopper warbler (Locustella portenta), the Peleng leaf warbler (Phylloscopus suaramerdu), and the Taliabu leaf warbler (Phylloscopus emilsalimi).

Holotype of Wulong bohaiensis, from Poust et al. (2020).

In February, a horned lark preserved in permafrost was identified. A series of isolated feathers and an avialan wing were reported from Burmese amber. (As I'll mention under March, Burmese amber would become a particularly hot topic later in the year.) A new specimen of Chirostenotes and a paraortygid from the Uinta Formation were described. Evidence of dietary plasticity in passenger pigeons was presented. Convergent evolution between the syrinxes of hummingbirds and songbirds was documented. The vocal sequences of African penguins were suggested to conform to linguistic laws. The nomenclature of Lophorina birds-of-paradise was reexamined. New studies came out on the taphonomy of feathers, inferring lifestyle from paravian claw curvature, locomotion in dromaeosaurids, the diversity of island birds, the origin of complex sociality in birds, introgression in the origin of the domestic chicken, the phylogeny of rails and waxbills, the shape of great auk eggs, the evolution of ornamentation in gulls, hearing in great cormorants, the aerodynamic role of raptor tails, the wing and tail musculature of barn owls, the evolution of plumage coloration in lorikeets and Australasian robins, hybridization among American crow lineages, the processing of encounters with dead conspecifics in American crows, social learning in Eurasian blue tits, and craniofacial integration in Hawaiian honeycreepers and Darwin's finches. Newly-named maniraptors included the Cretaceous euornithean Khinganornis hulunbuirensis, the white-winged tapaculo (Scytalopus krabbei), the jalca tapaculo (Scytalopus frankeae), and the Ampay tapaculo (Scytalopus whitneyi).

Pleistocene horned lark recovered from permafrost, from Dussex et al. (2020).

In March, a special volume on the evolution of feathers was published. A large oviraptorosaur from the Hell Creek Formation was described. The sensory systems of birds were reviewed. The Vaurie's nightjar was reevaluated as possibly belonging to the European nightjar. Evidence for statistical inference in kea was presented. A new classification for fluvicoline tyrant flycatchers was proposed. The supposed Pliocene longspur "Pliocalcarius" was reinterpreted as a species of the lark genus Eremophila. Red-winged blackbirds were shown to eavesdrop on the alarm calls of yellow warblers. New studies came out on snout morphology in dromaeosaurids, the modularity of the avian neck, the phylogeny of junglefowl, trochilin hummingbirds, and Scytalopus tapaculos, lung morphometrics in high-altitude waterfowl, the anatomy of rictal bristles in strisoreans, bill disparity in penguins, the evolution of migratory behavior in tyrant flycatchers, and phylogenetic signal in cowbird skulls. Newly-named maniraptors included the dromaeosaurid Dineobellator notohesperus, the Miocene pheasant Phasianus bulgaricus, the Miocene sandgrouse Linxiavis inaquosus, the Pleistocene owl Asio ecuadoriensis, and... yes, the Cretaceous pan-galloanseran Asteriornis maastrichtensis. Then there was the maniraptor that wasn't: Oculudentavis khaungraae, originally described as an avialan based on a skull preserved in Burmese amber, was quickly met with skepticism regarding its phylogenetic affinities. The paper was retracted in July, and a peer-reviewed study reassessing the specimen as a lizard was later released in October. In addition to the taxonomic controversy, the publicity that Oculudentavis received also sparked discussions about the human rights violations that often underlie the procurement of Burmese amber, resulting in official statements on the subject from scientific journals and organizations like the Society of Vertebrate Paleontology. Having been previously guilty myself of excitedly discussing Burmese amber discoveries without acknowledging the associated ethical issues, it's a topic that I've tried to treat with appropriate circumspection going forward.

Red-winged blackbird, photographed by Walter Siegmund, under CC BY-SA 3.0.

In April, red-billed oxpeckers were shown to warn black rhinos of approaching humans. A new specimen of Longusunguis and an owl from the Jebel Qatrani Formation were described. An enantiornithean foot was reported from, well... Burmese amber. Peramorphic features were identified in avian skulls. New studies came out on the ultramicrostructure of paravian teeth, the evolution of avian brain size, humeral disparity in birds, the genetic basis of avian foot feathering, the development of spinal nerves in avian tails and the olfactory system in chickens, the bone histology of elephant birds, the adaptive radiation of neoavians, the phylogeny of turacos and chlorophonias and euphonias, the diversification of babblers, adaptations to migration in the flight feathers of European robins, and speciation rates in tanagers.

Diagram showing black rhinos reacting to approaching humans when warned by red-billed oxpeckers, from Plotz and Linklater (2020).

In May, giant petrels were documented attacking sperm whales. An oviraptorosaur specimen preserved with associated eggs was reported. Evidence of ontogenetic dietary shifts in Deinonychus and iridescent plumage in Calciavis were presented. Avian wing shape was found to correlate with a variety of environmental and ecological factors. A possible case of a common cuckoo being killed by mobbing from a great reed warbler was recorded. New specimens of Anhinga pannonica were described. Avian scavengers were suggested to use auditory cues to help locate food. The classification of xolmiin tyrant flycatchers was revised. Black-capped chickadees were shown to be able to identify female conspecifics by call. New studies came out on pelvic morphology of caenagnathid oviraptorosaurs, the cranial osteology of Sapeornis, the anatomy of Parahesperornis, scaling trends in avian alular feathers, the evolution of avian developmental durations, the development of the avian vertebral column, webbed feet in waterbirds, and flight feather positioning, the genetic basis of reduced lifespans in flightless birds, the phylogeny of kiwi, lorikeets, bowerbirds, and nuthatches, introgression within bean geese, the diversification of frogmouths, and biomechanical diversity in kingfishers. Newly-named maniraptors included the basal paravian Overoraptor chimentoi, the basal avialan Kompsornis longicaudus, the recently extinct New World vulture Coragyps seductus, the recently extinct accipitrids Gigantohierax itchei, Buteogallus royi, and Buteo sanfelipensis, the recently extinct caracara Milvago diazfrancoi, the Oligocene piciform Jacamatia luberonensis, the Pleistocene troupial Icterus turmalis, and the Pleistocene cowbird Molothrus resinosus.

Northern giant petrel attacking sperm whale, from Towers and Gasco (2020).

In June, the osteology of penguins and plotopterids was compared. The osteology of Rahonavis was described in detail. An ornithuran from the Dinosaur Park Formation, a new specimen of Struthio karatheodoris, and a tyrannidan passeriform from the Oligocene of France were reported. The development of avian flight behaviors and the role of extended parenting in the evolution of corvid cognition were reviewed. Broad-tailed hummingbirds were shown to be able to disciminate non-spectral colors. The endocast of the night parrot was described. New studies came out on chemical preservation in the tail feathers of Anchiornis, the scaling of the avian middle ear, the genetic basis of sexual dichromatism in birds, casque ontogeny in southern cassowaries, the phylogeny of hill partridges, the origin of the domestic chicken, convergent responses to flightlessness in rails, flight efficiency in auks, the mandibulosphenoidal joint in penguins and procellariiforms, inbreeding avoidance in long-tailed tits, and the evolution of Aimophila and Peucaea New World sparrows.

Ontogeny of the casque in the southern cassowary, from Green and Gignac (2020).

In July, high-frequency hearing was documented in Ecuadorian hillstars. Evidence of sequential molting in Microraptor was presented. A juvenile dromaeosaurid from the Prince Creek Formation, a new specimen of Protopteryx, and a crane from the Miocene of Germany were described. Soft tissue analyses were used to support the identification of ovarian follicle preservation in Mesozoic avialans. A partial enantiornithean specimen was reported from (one more time...) Burmese amber. The syrinx of the black jacobin was visualized. A sense of numerical ordinality was found in rufous hummingbirds. Visual adaptations in raptors were reviewed. The classification of lorikeets was revised. The songs of thrush nightingales were found to share categorical rhythms with human music. Birdsong learning was shown to be beneficial to both tutees and tutors in song sparrows. New studies came out on variation in Mesozoic feathers (note: based on Burmese amber specimens), facial pneumaticity in dromaeosaurids, the endocranial anatomy of Velociraptor, sub-surface foot kinematics in birds, the morphology of avian flight feathers, the evolution of ostriches, eggshell coloration in tinamous, flight performance in Andean condors, the phylogeny of Dendrocolaptes ovenbirds, host mimicry in viduids, and cultural evolution in the song of white-throated sparrows. Newly-named maniraptors included the alvarezsaur Trierarchuncus prairiensis, the oviraptorosaur Citipes (a new genus for "Leptorhynchos" elegans), the Pleistocene pheasant Chauvireria bulgarica, the recently extinct pigeon Tongoenas burleyi, the Eocene owl Primoptynx poliotauros, the Ayacucho antpitta (Grallaria ayacuchensis), the Oxapampa antpitta (Grallaria centralis), the Puno antpitta (Grallaria sinaensis), the Chamí antpitta (Grallaria alvarezi), the Graves's antpitta (Grallaria gravesi), and the O'Neill's antpitta (Grallaria oneilli).

Preserved gap in wing feathers of Microraptor, interpreted as indicative of molting pattern, from Kiat et al. (2020).

In August, a special volume on pennaraptoran paleontology was published. The potential for powered flight was assessed in Mesozoic maniraptors. Expanded sternal ribs were documented in Jeholornis. The birds from the Eocene of the Geiseltal and avian macroevolution were reviewed. Large brains were shown to be linked to increased lifespan in birds. Fork-tailed flycatchers were found to produce sounds using their wing feathers. Red-billed queleas were reported to be able to tolerate higher temperatures than any other bird. New studies came out on rates of skull evolution in birds (and other dinosaurs), the correlation of down feather morphology with habitat and temperature, squamosal morphology in birds, the phylogeny of crown birds, pheasants, and elanine kites, the evolution of host use in avian brood parasites and breeding plumages in New World warblers, the flight behavior of Anna's hummingbirds through waterfalls, the diversification of penguins, the genetic basis of nocturnal adaptations in owls, the cranial anatomy of Otus murivorus, and ecosystem engineering by superb lyrebirds. Newly-named maniraptors included the Pleistocene–Holocene coot Fulica montanei, the Pliocene penguin Eudyptes atatu, the Eocene accipitrid Palaeoplancus dammanni, and the Pleistocene barn owl Tyto maniola.

Phylogeny of paravians, with lineages potentially capable of powered flight highlighted, from Pei et al. (2020).

In September, the isolated holotype feather of Archaeopteryx was argued to indeed belong to Archaeopteryx, contrary to a previous study from 2019. A new specimen of Piscivorenantiornis was described. Avian endocasts were shown to be reliable proxies for the sizes of corresponding brain regions. A cortex-like canonical circuit in the avian forebrain was identified and a neural correlate of sensory consciousness was reported in carrion crows. Avian plumage patterns were reviewed. Extreme torpor was documented in Andean hummingbirds. Breeding success was shown to correlate with divorce in plovers. Azure-winged magpies were found to share food with conspecifics depending on availability of food to the recipient. New studies came out on skull modularity in birds (and other archosaurs), hindlimb morphometrics in avialans, beak morphology in Confuciusornis, phylogenetic signal in the lacrimal/ectethmoid of waterfowl, ossification sequences in black-headed gulls and Eurasian reed warblers, vertebral pneumaticity and serial variation in storks, the evolution of growth patterns in passeriforms, and the phylogeny of stipplethroats. Newly-named maniraptors included the Pleistocene–Holocene New World vulture Cathartes emsliei, the Pliocene–Pleistocene owl Glaucidium ireneae, and the Pliocene–Pleistocene corvid Corvus bragai.

Black metaltail, which during torpor attains the lowest body temperature recorded of any bird, photographed by Mickaël Villemagne, under CC BY-NC 4.0.

In October, the aerodynamics of scansoriopterygids were assessed. A shark-bitten hesperornithiform, giant pelagornithids from the Eocene of Antarctica, and large New World vultures from the Pleistocene–Holocene of Uruguay were described. Visual adaptations in birds were shown to correlate with foraging niche in the Peruvian Andes. Differences in visual adaptations between predatory and scavenging raptors were reviewed. Cryptic sexual dimorphism was recorded in Sulawesi babblers. New studies came out on vertebral pneumaticity in Nothronychus, contact incubation in troodontids, plantar adaptations of bird feet, the gust-rejecting mechanism of bird wings, Quaternary avian extinctions in the Bahamas, group organization in foraging phalaropes, the demographic histories of condors, the evolution of communication signals in woodpeckers, and species delimitation in Alaudala larks. Newly-named maniraptors included the oviraptorosaur Oksoko avarsan, the Eocene waterfowl Cousteauvia kustovia, the Eocene possible stem-charadriiform Nahmavis grandei, the plotopterids Empeirodytes okazakii and Stenornis kanmonensis, and the Oligocene accipitrid Aviraptor longicrus. A paper I co-authored also got published this month, in which we proposed a phylogenetic taxonomy of strisoreans.

Holotype of Aviraptor longicrus, from Mayr and Hurum (2020).

In November, the wing musculature of flightless auks was reconstructed. New specimens of Trierarchuncus were described. Feathers preserved in amber were reported... not from Myanmar, but from the Escucha Formation in Spain. Putative ovarian follicle preservation in Mesozoic avialans was again disputed (in response to the earlier paper from July). A large dataset of avian genomes was published. Migratory birds (and mammals) were found to have faster paces of life than non-migratory species. Ecomorphology was shown to correlate with diversity in corvidean passeriforms. New studies came out on group movement and decision-making in vulturine guineafowl, the evolution of the Galápagos rail, the phylogeny of manakins, species delimitation in Calandrella larks, auditory memory in zebra finches, and introgression in Setophaga New World warblers. Newly-named maniraptors included the enantiornithean Falcatakely forsterae (with a highly unusual skull), the gastornithid Gastornis laurenti, the recently extinct sandpiper Prosobonia sauli, the South Georgia gentoo penguin (Pygoscelis poncetii), and the Miocene accipitrid Vinchinavis paka.

Holotype of Falcatakely forsterae, from O'Connor et al. (2020).

In December, evidence of tactile foraging in lithornithids was presented. An oviraptorosaur preserved on top of an embryo-bearing egg clutch, a Saurornitholestes specimen from the Judith River Formation, a new specimen of Macranhinga, and a hornbill from the Miocene of Uganda were described. Interpreting molting patterns from exceptionally-preserved maniraptor fossils appears to be all the rage now, as evidence of sequential molting was also reported in Archaeopteryx. Cartilage preserved on the wishbone of Confuciusornis was documented. Male superb fairywrens were found to maintain vibrant breeding coloration regardless of individual quality. New studies came out on the development of the avian ankle, anthropogenic extinctions of flightless birds, the evolution of paleognath mitogenomes, endocranial ontogeny in ostriches (and alligators), the anatomy of the respiratory system in ostriches (and alligators), the evolutionary history of junglefowl, song frequency in passeriforms, the diversification of suboscines, and the phylogeny of doraditos and white-eyes. Newly-named maniraptors included the Cretaceous euornitheans Abitusavis lii and Similiyanornis brevipectus and the recently extinct owl Ornimegalonyx ewingi.

Oviraptorid preserved on top of egg clutch, from Bi et al. (in press).