New (Extinct) Maniraptors of 2021

By my count, 42 new species of extinct maniraptors were named in 2021, which is about par for the course these days. Let's take a quick look at these new taxa and other nomenclatural proposals.

Alvarezsaurs
New alvarezsaurs have been described at a fairly steady trickle in recent years, and 2021 gave us Khulsanurus, known from a partial skeleton from the Late Cretaceous Barun Goyot Formation of Mongolia. It was discovered at the same locality as Parvicursor, but can be distinguished based on vertebral anatomy.

Oviraptorosaurs
No new oviraptorosaur species were described last year; in fact, they may have lost a member. A new specimen of Elmisaurus preserves overlapping material nearly identical to Nomingia, lending credence to the hypothesis that the two are synonymous (in which case the name Elmisaurus would take priority).

Non-ornithothoracean Paravians
2021 was a good year for dromaeosaurids, with the velociraptorines Shri (formerly known by the nickname "Ichabodcraniosaurus") and Kuru (formerly known by the nickname "Airakoraptor") both described based on partial skeletons from the Barun Goyot Formation. Less completely known are Kansaignathus (based on a partial jaw and possibly teeth from the Late Cretaceous Yalovach Formation of Tajikistan), Vectiraptor (based on partial vertebrae from the Early Cretaceous Wessex Formation of the United Kingdom), and Ypupiara (an unenlagiine based on jaw fragments from the Late Cretaceous Serra da Galga Formation* of Brazil). Tragically, the type specimen of Ypupiara was among the fossils lost in the 2018 fire that destroyed the main building of the National Museum of Brazil.

*Ypupiara was described as being from the Marília Formation. However, it was recently proposed that the classic Marília Formation should be split into the separate Marília and Serra da Galga Formations.

Holotype of Shri, from Turner et al. (2021).

Troodontids, on the other hand, got Papiliovenator from the Late Cretaceous Wulansuhai Formation of China, known from a partial skeleton including a nearly complete skull. Its name translates (I think quite adorably) into "butterfly hunter", not based on any inference about its ecology, but on the "butterfly-like" shape of its dorsal vertebrae. There was also Tamarro from the Late Cretaceous Talarn Formation of Spain, known from a partial metatarsal. Meanwhile, a detailed reassessment of small theropods from the Dinosaur Park Formation concluded that Latenivenatrix cannot be reliably distinguished from Stenonychosaurus, and that the two should be (re-)synonymized.

Skull of Papiliovenator, from Pei et al. (2022). (The paper was released as an advance online publication in 2021.)

Last year also saw the description of a new Jeholornis-like avialan, Neimengornis, from the Early Cretaceous Jiufotang Formation of China. It appears to be known from an essentially complete skeleton. However, there have already been suggestions that the type specimen is likely a chimera.

Enantiornitheans
As is often the case, the Jiufotang Formation also contributed some new enantiornitheans in 2021, two to be precise. One of these was Brevirostruavis, which is notable for preserving an elongated hyoid, suggesting that it may have used its tongue for handling food. Although the original description compares this condition to that seen in hummingbirds and woodpeckers, the hyoid elongation seen in Brevirostruavis does not look to my eye quite as extreme as that of those crown birds. My guess would be that Brevirostruavis might have used its tongue to help pick up food and manipulate it within its mouth, but did not use a feeding strategy that involved protruding the tongue very far beyond its snout.

The other new Jiufotang enantiornithean was Yuanchuavis, which preserves a set of eight tail feathers forming a fan-like array. This contrasts with the typical condition seen in most other enantiornitheans (which tended to either lack large tail feathers or have only a single pair of them), but resembles that of Chiappeavis. Unlike Chiappeavis, the central pair of tail feathers in Yuanchuavis was particularly elongate.

Personally, I think one of the most scientifically important new maniraptors to be named last year was Yuornis from the Late Cretaceous Qiupa Formation of China. It is based on a partial skeleton with an essentially complete skull preserved in three dimensions, a rarity for avialan fossils. It is also one of the few enantiornitheans known to have had entirely toothless jaws.

Holotype of Yuornis, from Xu et al. (2021).

A fourth enantiornithean to come out of 2021 was Fortipesavis, known from a foot preserved in Late Cretaceous Burmese amber that had been previously described in 2019.

Non-neornithean Euornitheans
Two non-neornithean euornitheans were named in 2021 based primarily on cranial material, these being Brevidentavis and Meemannavis from the Early Cretaceous Xiagou Formation of China. The type specimen of Brevidentavis was previously reported as the skull of Gansus, but a more likely candidate for an actual Gansus skull was described in the new paper. The lower jaw of Brevidentavis exhibits unusually short, blunt teeth set in a groove (instead of in sockets), whereas Meemannavis has a toothless lower jaw.

Holotype of Brevidentavis, from O'Connor et al. (in press).

One Mesozoic avialan named last year that was not discovered in Asia was Kaririavis from the Early Cretaceous Crato Formation of Brazil. Based on a partial foot, it was unusual for a Cretaceous euornithean in being particularly small (around the size of a sparrow) and in that its one preserved toe claw was large and strongly curved.

Paleognaths
Perhaps one of the biggest overhauls in dinosaur systematics in 2021 was the reinterpretation of geranoidids, eogruids, and ergilornithids as stem-ostriches instead of gruiforms. Although a close relationship between ergilornithids and ostriches had been suggested in the 1950s and contemplated more recently in light of further data on fossil paleognaths, anatomical information from newly described eogruid and ergilornithid specimens seems to strongly bolster this hypothesis. In their revision of these birds' affinities, the authors additionally resurrected the genus Proergilornis, which had been previously synonymized with Ergilornis, and suggested that it was less closely related to extant ostriches than ergilornithids proper.

A new fossil paleognath was also described last year, the kiwi Apteryx littoralis, based on a tarsometatarsus from the Pleistocene of New Zealand. Kiwi fossils are rarely found, and this species is the first one known from the early Pleistocene.

Galloanserans
A couple of extinct total-group anseriforms were named in 2021. One of these was the small presbyornithid Bumbalavis from the Eocene Naran-Bulak Formation of Mongolia. (Meanwhile, the type specimen of "Presbyornis" mongoliensis from the same locality was reinterpreted as a stem-mirandornithean similar to Juncitarsus.) The other was the stiff-tailed duck Manuherikia primadividua from the Miocene Bannockburn Formation of New Zealand, the fourth species to be named in the genus Manuherikia. It appears to be stratigraphically separated from the older M. lacustrina.

Two small, early total-group galliforms were described from the Naran-Bulak Formation last year as well, these being Bumbanipodius and Bumbanortyx.

Strisoreans
New fossil members of Strisores don't get described every day, or every year for that matter. (The last one I recall was Cypseloramphus from 2016.) That's why I was excited to see the publication of Archaeodromus from the Eocene London Clay Formation of the United Kingdom, known from a partial skeleton. This new taxon is a member of Archaeotrogonidae (formerly thought to be a group of stem-trogons, as their name suggests, later reevaluated as strisoreans), and not only provides new anatomical information on this group, but also suggests that they may be stem-nightjars. The absence of clear examples of Eocene stem-nightjars had been a conspicuous gap in the known fossil record of Strisores, so the common but enigmatic archaeotrogonids filling that space seems like a tantalizing possibility. It would also imply that my earlier hypothesis that the putative archaeotrogonid Hassiavis was a stem-owlet-nightjar is probably wrong, but that's the way science goes sometimes.

Shoulder and forelimb bones of Archaeodromus, from Mayr (2021).

Gruiforms
The Naran-Bulak Formation gave us two more new fossil birds in 2021, the possible gruiforms Bumbanipes and Bumbaniralla. Bumbanipes appears to have been a specialized swimming form with morphological similarities to the limpkin (Aramus guarauna) and finfoots, whereas Bumbaniralla resembles messelornithids. Additional new entrants in the extinct gruiform department were the crane-like Palaeogeranos, based on a coracoid from the Oligocene of France, and the recently extinct rail Gallirallus astolfoi, based on a tarsometatarsus from the island of Rapa Iti in French Polynesia. Recent revisions in the generic assignment of recent rails have restricted the genus Gallirallus to the weka (G. australis) and sometimes the New Caledonian rail (G. lafresnayanus), in which case it wouldn't surprise me if G. astolfoi was transferred to a different genus in the future, perhaps Hypotaenidia. In fact, reassignment to Hypotaenidia was proposed last year for another recently extinct rail, the Chatham rail ("Cabalus" modestus), in one study on rail phylogeny.

Charadriiforms
No new extinct charadriiforms were named in 2021, but a study on the original illustrations used to describe the Moorea sandpiper (Prosobonia ellisi) supported synonymizing it with the Tahiti sandpiper (P. leucoptera).

Natatoreans
There has still been no formal proposal to name the clade uniting Phaethontimorphae and Aequornithes, but last year the name Feraequornithes was coined for the group including most aequornitheans other than loons. As it happens, all of the extinct members of the "waterbird clade" that were named in 2021 belong to Feraequornithes.

The excellent fossil record of total-group penguins continued to provide, with new taxa in the form of the giant Kairuku waewaeroa, based on a partial skeleton from the Oligocene Glen Massey Formation of New Zealand, and the smaller Marambiornopsis, based on a tarsometatarsus from the Eocene Submeseta Formation of Antarctica. Perhaps more surprising was the description of a new fossil petrel based on a well-preserved skeleton, Procellaria altirostris from the Pliocene Tangahoe Formation of New Zealand.

Holotype of Procellaria altirostris, from Tennyson and Tomotani (2021).

Among pelecanimorphs, Eopelecanus was described as the oldest known stem-pelican based on a tibiotarsus from the Eocene Birket Qarun Formation of Egypt, whereas a revision of plotopterid specimens from the Paleogene of Washington State resulted in "Tonsala" buchanani being reassigned to Klallamornis.

Telluravians
Although not as many new raptors were named last year as there were in 2020, they were still pretty well represented. Arguably the most exciting was Archaehierax, known from a partial skeleton from the Oligocene Namba Formation of Australia. It was nearly as big as the wedge-tailed eagle (Aquila audax, the largest bird of prey in Australia today), and phylogenetic analyses (which have otherwise almost never been done on fossil accipitrimorphs!) suggest that it was a crown accipitrid, but not especially closely related to any living species.

Tarsometatarsus of Archaehierax, from Mather et al. (in press).

The other new fossil accipitrids of 2021 were also quite large species, Buteo dondasi from the Pliocene Chapadmalal Formation of Argentina and Buteogallus irpus from the Pleistocene of the Dominican Republic and Cuba. B. irpus is notably based on specimens formerly assigned to Titanohierax (now restricted to fossils from the Bahamas) and "Amplibuteo" woodwardi (now restricted to fossils from the United States). Its description further suggested sinking members of the genus Amplibuteo into Buteogallus, which had been foreshadowed in previous papers. Another new raptor was the owl Margarobyas abronensis from the Pleistocene of Cuba, a close relative of the poorly-known bare-legged owl (M. lawrencii) that still lives in Cuba today.

Among coraciimorphs, there was Ueekenkcoracias from the Huitrera Formation of Argentina, based on a partial hindlimb. It was described as a stem-member of the group uniting ground rollers and rollers, in which case it would be the first representative of this clade known from South America. However, a later study argued that Ueekenkcoracias more closely resembles the enigmatic Eocene bird Palaeopsittacus, in which case it may not be a telluravian at all. Probably less controversial are the three Pleistocene woodpeckers described from the La Brea tar pits (listed in order of decreasing body size), Breacopus, Melanerpes shawi, and Bitumenpicus.

The London Clay Formation had a good year as far as new fossil birds were concerned, with Tynskya waltonensis revealing new details about messelasturid morphology, though the phylogenetic affinities of these parrot-like birds remain mysterious. Perhaps even more remarkable was the psittacopedid Parapsittacopes, known from a very well-preserved partial skeleton that sheds new light on the anatomy of these stem-passeriforms. It further adds to the already impressive ecological diversity of psittacopedids, exhibiting a slightly widened beak that may have allowed it to feed on fruits and flying insects.

Skull of the holotype of Parapsittacopes, from Mayr (2020). (The print version of the journal retroactively dates the paper to 2020, but really, the paper was first released in 2021.)

Last but not least, a few fossil crown passeriforms were also described in 2021, the possible suboscine Crosnoornis, based on a nearly complete skeleton from the Oligocene of Poland, and the magpie Pica praepica from the Pleistocene of Bulgaria.

Type specimen of Crosnoornis, from Bochenski et al. (2021).

New (Extinct) Maniraptors of 2019

A longstanding tradition on this blog was to poll readers on their favorite newly-named maniraptors of the previous year. Following the removal of Blogger's poll widget, I was forced to discontinue this tradition. Last year, I tried out a different way of honoring new taxa by writing a paragraph about every extinct maniraptor named in 2018.

I received some positive feedback for this new format, but I'm thinking that I'll change it up again this year. Drafting a paragraph on every new species required me to spend roughly the same amount of time on species known from a single, fairly nondescript bone as those known from essentially complete or particularly bizarre specimens. Although nearly all fossil descriptions have some scientific value, I suspect that isolated coracoids are generally not of as much interest to most of my readers.

This year, I will instead divide this post up into several sections based (approximately) on phylogeny, and briefly discuss each new maniraptor of 2019 under the relevant section. Every new species of extinct maniraptor that was named last year will at least get a mention, but I won't make myself write a full paragraph on each one. This will probably also result in a shorter post that is presumably less daunting to read... though writing about more than forty species produces a sizable post no matter how it's sliced.

Alvarezsaurs
Two new theropods were described as alvarezsaurs last year, which is a decent number considering that 2013-2017 went without any new alvarezsaurs being named (with the possible exception of Aorun, which wasn't originally recognized as an alvarezsaur). One of the 2019 alvarezsaurs, Shishugounykus, hails from the Late Jurassic Shishugou Formation of China, making it one of the oldest known alvarezsaurs alongside Haplocheirus and potentially Aorun. Shishugounykus is known from a partial skeleton, including a nearly complete hand, and appears to have been more distantly related to the Late Cretaceous alvarezsaurids than Haplocheirus was. Given the famously bizarre anatomy of alvarezsaurids, any finding that sheds light on their origins is a welcome one.

That's assuming, of course, that Shishugounykus was indeed an alvarezsaur. The phylogenetic analysis in the description of the troodont Hesperornithoides (discussed later in this post) recovered Aorun and Haplocheirus as compsognathids instead of alvarezsaurs, and Shishugounykus reportedly comes out as a compsognathid in that dataset, too. In contrast, a recent unpublished iteration of Andrea Cau's dataset corroborates an alvarezsaur identity for both Haplocheirus and Shishugounykus.

The other new alvarezsaur of 2019 was Nemegtonykus, which was also named after the geologic formation it was found in, the Late Cretaceous Nemegt Formation of Mongolia. Prior to the description of Nemegtonykus, the only alvarezsaur previously known from the Nemegt had been Mononykus. The holotype of Nemegtonykus is a partial skeleton including much of the tail, trunk, and left hindlimb. It exhibits patterns of bone fusion in the hip, shoulder girdle, and feet that are unique among alvarezsaurs.

Skeletal reconstruction of Nemegtonykus showing preserved elements, from Lee et al. (2019).

Therizinosaurs
Therizinosaurs are another group of maniraptors for which new species are described relatively infrequently. Last year gave us Lingyuanosaurus from the Early Cretaceous Jehol Biota of China, known from some vertebrae and partial limbs. The holotype is quite small (coyote-sized), though it probably represents a juvenile. The specimen is incomplete enough that it is unclear whether it really was a therizinosaur; Mickey Mortimer found it as an oviraptorosaur using the Hesperornithoides dataset, but also noted that a therizinosaurian identity was only slightly less parsimonious.

Oviraptorosaurs
In recent times oviraptorosaurs have usually gotten away with at least one or two new entries every year. Two were described in 2019. One was Xingtianosaurus from the Early Cretaceous Yixian Formation of China, a Caudipteryx-like form known from a partial skeleton with incompletely preserved wing feathers. The other was Gobiraptor from the Nemegt Formation, known from partial remains of the skull, hip, limbs, and tail. Bone histology suggests that the holotype of Gobiraptor was an immature individual, but, at over a meter in length, it was already larger than the adults of many other oviraptorosaurs. Oviraptorosaur researcher Greg Funston has mentioned on social media that unpublished evidence indicates that Gobiraptor is actually the same species as a previously-named oviraptorosaur.

Basal Paravians
2019 was a good year for what Justin Tweet calls "coming attractions" in dinosaur paleontology, which are essentially fossil dinosaurs known to the paleontological community through brief descriptions, conference presentations, and word of mouth, but have yet to receive a formal name. Although not all of them were included in Tweet's list (which was not meant to be exhaustive), I would consider the ornithopod Convolosaurus, the sauropod Wamweracaudia, the allosauroid Asfaltovenator, and the tyrannosauroid Suskityrannus to all qualify as long-standing "coming attractions" that were finally named last year.

Several maniraptoran "coming attractions" came to light in 2019 as well. One of these was the so-called "Naze dromaeosaurid", known from a foot from the Late Cretaceous Snow Hill Island Formation in Antarctica. First mentioned publicly in 2005 and then briefly described in 2007, this dinosaur was formally named Imperobator last year. Despite its original nickname, the describers of Imperobator found its precise phylogenetic position within Paraves difficult to place, and Andrea Cau has argued that it may not even be a maniraptor at all. The title of the paper that named Imperobator called it a "gigantic" paravian, yet its visible dimensions are comparable to those of Deinonychus. That's larger than average for a paravian, but "gigantic" may be overstating it.

One of the most highly anticipated "coming attractions" described last year was Hesperornithoides, a troodont from the Late Jurassic Morrison Formation of the United States. First announced in a conference abstract in 2004, Hesperornithoides (then nicknamed "Lori") was a big deal for several reasons, particularly the fact that Jurassic paravians other than Archaeopteryx were essentially unknown at the time. With the discovery of Anchiornis and its ilk since then, this is no longer the case, but Hesperornithoides remains notable for the three-dimensional preservation of its skeletal elements (as opposed to the flattened state anchiornithids tend to be preserved in) and for being the best-represented Jurassic paravian from North America.

Skeletal reconstruction of Hesperornithoides showing preserved elements, from Hartman et al. (2019).

Hesperornithoides also generated some buzz for the phylogenetic analysis that accompanied its description. The dataset used has greater taxon sampling than any other published analysis of Mesozoic theropods (it includes nearly all Mesozoic maniraptoromorphs known at the time of study and even a handful of Cenozoic birds), and originated from reevaluating the Theropod Working Group phylogenetic dataset, which has been the basis for the majority of Mesozoic theropod analyses. This resulted in several novel findings, such as Haplocheirus as a compsognathid (as mentioned previously) and Pelecanimimus as an alvarezsaur. Time will tell whether these results hold up, but this analysis highlights the importance of independently evaluating phylogenetic datasets, as repeatedly building directly on previous datasets can create an illusion of consensus.

Strangely enough, no new (definite) dromaeosaurids were named in 2019. Someone drew the short end of the stick.

Basal Avialans
In recent times, Archaeopteryx has generally been considered the only known paravian from the Late Jurassic of Germany, but this has started to change in the past few years. In 2017, one supposed Archaeopteryx specimen was reevaluated as an anchiornithid and given the new genus Ostromia. Last year added another new paravian to the lineup, Alcmonavis from the Mörnsheim Formation. Although it is known only from a forelimb, Alcmonavis appears to differ from Archaeopteryx in the robusticity of certain bones as well as the prominence of various muscle attachment sites.

Another exciting find in the Mesozoic avialan department was Fukuipteryx from the Early Cretaceous Kitadani Formation of Japan. Not only is it the first Early Cretaceous avialan to be found in Japan, Fukuipteryx is known from a partial, three-dimensionally preserved skeleton including much of the front and hind limbs. Despite having a short tail with a pygostyle, it was found to have been less closely related to modern birds than the long-tailed Jeholornis was, which may indicate that the pygostyle evolved more than once among avialans, as some other recent studies have suggested.

Skeletal reconstruction of Fukuipteryx showing preserved elements, from Imai et al. (2019).

Enantiornitheans
The "opposite birds" had a good showing last year, and probably the most intriguing new taxon was Elektorornis from the Late Cretaceous of Myanmar, known from hindlimbs and wing feathers preserved in amber. Burmese amber has produced some of the most spectacular fossils of Mesozoic dinosaurs in recent years, including partial specimens of juvenile enantiornitheans and the tail of a non-pygostylian theropod, but Elektorornis is the first of these fossils to be named. It had an unusually long third toe, which the authors suggest may have been used as a probing tool for foraging. It is likely also the smallest known mature Mesozoic dinosaur, the holotype being of comparable size to juvenile enantiornitheans from the same locality despite apparently being an adult or subadult.

Holotype of Elektorornis, from Xing et al. (2019).

Also particularly interesting was Avimaia from the Early Cretaceous Xiagou Formation of China. The holotype is a partial skeleton preserved with an unlaid egg, a first for Mesozoic avialans. Furthermore, histological examination of the egg revealed a double-layered eggshell, indicating that the unfortunate individual had likely died from egg binding (a usually fatal condition in which an unlaid egg is retained for an abnormally long time). A second specimen of Avimaia had been previously described in 2006, but had not been named.

Holotype of Avimaia, from Bailleul et al. (2019). Note the unlaid egg preserved in its body cavity.

As usual, the Jehol Biota did not skimp on enantiornitheans, giving us the relatively large (pigeon-sized) Gretcheniao and the smaller Mirusavis and Shangyang. Mirusavis is noteworthy for preserving medullary bone (produced by female birds before and during egg laying) throughout much of the skeleton, a more extensive distribution of this type of bone than seen in many modern birds.

Although not newly discovered, another Jehol enantiornithean that was given a new name in 2019 was Camptodontornis. It had been originally named "Camptodontus" in 2010, but this genus turned out to be preoccupied by a beetle. It is likely that Camptodontornis is the same as Longipteryx though, as had already been suggested by other studies.

Mesozoic Euornitheans
An unusual euornithean described last year was Mengciusornis from the Early Cretaceous Jiufotang Formation of China. Its teeth were large and curved, but restricted to the tip of the upper jaw. This deviates from the typical pattern in toothed euornitheans, in which the upper jaw tip was usually toothless.

Holotype of Mengciusornis, from Wang et al. (2019).

More closely related to modern birds were Antarcticavis from the Snow Hill Island Formation, known from a partial skeleton, and Kookne from the Late Cretaceous Chorrillo Formation of Argentina, known from a partial coracoid. The describers of Kookne suggest that it may even be a neognath, as it shares some similarities with waterfowl, but this is naturally difficult to verify with such a fragmentary specimen.

Paleognaths
One extinct paleognath was named last year, the emu Dromaius arleyekweke from the Miocene Waite Formation of Australia. Known mainly from hindlimb bones, D. arleyekweke was smaller than modern emus and cassowaries (even the dwarf cassowary). Its feet were proportionately very long, however, indicating that it was probably a fast runner.

Galloanserans
Among the galloanserans described last year was what I consider to be one of the most scientifically important new dinosaurs of 2019, the stem-waterfowl Conflicto from the Paleocene López de Bertodano Formation of Antarctica. It is the oldest unequivocal total-group anseriform known from well-represented remains, and may provide evidence that a long-legged, flat-billed body plan was ancestral to all modern waterfowl (including the unusual screamers). I wrote about Conflicto in more detail here. Another Paleocene waterfowl was described last year, the large (swan-sized) Naranbulagornis from Mongolia. It is far less completely known, represented only by a partial carpometacarpus and femur.

Skull of Conflicto, from Tambussi et al. (2019).

On the galliform side of things, 2019 gave us Xorazmortyx from the Eocene of Uzbekistan, which is only known from a partial coracoid. Its describers suggest that it belonged to a group of stem-galliforms called paraortygids, in which case it would be the first paraortygid known from Asia. Better remains are known for a trio of quail from the Macaronesian Islands, Coturnix alabrevis, C. centensis, and C. lignorum. These quail likely went extinct in historic times (within the last 1000 years) due to human activity. Their short wings suggest that they may have been flightless, which would have made them vulnerable to invasive predators.

Columbimorphs
The early fossil record of pigeons and their kin remains stubbornly sparse, but last year did welcome a new species of recently extinct pigeon, Ducula shutleri from Tonga. Known from sites dated to nearly 3000 years old, D. shutleri was the largest known member of the genus Ducula (the imperial pigeons), probably weighing over 1 kg. Despite its large size, there is no evidence that it had reduced flight capabilities.

Gruiforms
Last year we got a new member of the enigmatic Eogruidae, Sinoergilornis from the Miocene Liushu Formation of China. The life appearance of eogruids is mysterious, as they are known mostly from hindlimb bones, and unfortunately Sinoergilornis does not break that curse. Like some other eogruids, Sinoergilornis had only two toes per foot. Although I provisionally treat eogruids as gruiforms here, another study from last year noted that their assignment to Gruiformes is weakly based.

Two species of recently extinct, flightless rails were also described last year, Dryolimnas chekei from Mauritius and the large (chicken-sized) Hypotaenidia vavauensis from Tonga.

Charadriiforms
Surprisingly, given their diversity and frequent association with aquatic habitats, shorebirds have a relatively poor fossil record, but we did get a new fossil taxon in 2019, Cherevychnavis from the Miocene of Ukraine. Although it is very fragmentary (known only from a coracoid and partial humerus), it is notable for likely being a member of Charadrii (a group that also includes plovers, oystercatchers, etc.), which have a scant fossil record even by shorebird standards.

Ardeans
If any crown-bird group can claim to have a good fossil record, it's the penguins, and last year we gained three new species of extinct penguin, all from New Zealand. Two of these, the giant ?Crossvallia waiparensis from the Waipara Greensand and the smaller Kupoupou from the Takatika Grit, were from the Paleocene, making them some of the oldest known penguins. The third new penguin was Eudyptes warhami, a species of crested penguin that probably went extinct within the last 500 years.

The closest living relatives of penguins, the procellariiforms (petrels, albatrosses, etc.), have a decidedly worse fossil record. As such, the small albatross Aldiomedes from the Pliocene Tangahoe Formation of New Zealand was a pleasant surprise, especially seeing as it is known from a well-preserved skull. Its narrow beak suggests that it may have been more specialized for fish-eating than extant albatrosses (which feed more on squid).

Holotype of Aldiomedes, from Mayr and Tennyson (2019).

Two other waterbirds described last year were the ibis Geronticus thackerayi from the Pliocene-Pleistocene of South Africa, known from numerous (but often fragmentary) bones, and the heron Taphophoyx from the Miocene of the United States, only known from a coracoid and scapula.

Telluravians
The afroavian side of Telluraves only presented one new fossil species last year, but it was a good one: ?Laurillardia smoleni, a small stem-member of Upupides (hoopoes and woodhoopoes) from the Oligocene Tylawa Limestones of Poland. Not only is it known from a nearly complete specimen, the genus Laurillardia had been in severe need of a modern reevaluation.

Holotype of ?Laurillardia smoleni, from Mayr et al. (2019).

Things were more active on the australavian side, with the parrot Heracles from the Miocene Bannockburn Formation of New Zealand receiving substantial press attention. Heracles is known only from partial hindlimb bones, but these are enough to suggest a body mass of around 7 kg, making it the largest known parrot to have ever existed.

2019 was a good year for stem-passerines. The finch-like beaks of the Eocene Eofringillirostrum boudreauxi and E. parvulum showed that stem-passerines had evolved into seed-eating specialists long before true passerines did. E. boudreauxi was found in the Green River Formation of the United States, whereas E. parvulum was found in the Messel Formation of Germany. I wrote about these two species in more detail here. Another new stem-passerine was Zygodactylus ochlurus from the Oligocene Renova Formation of the United States, the youngest known stem-passerine from North America.

Holotype of Eofringillirostrum boudreauxi, from Ksepka et al. (2019).

Among crown-passerines, there was Dasyornis walterbolesi from the Miocene of Australia, the oldest known member of the bristlebirds, a poorly-studied group of Australian songbirds.

Miscellanea
The scansoriopterygids from the Late Jurassic of China continue to prove difficult to place phylogenetically. Already considered unusual since their discovery in 2002, scansoriopterygids rocked the paleontological world again in 2015 with the description of Yi, which appeared to preserve membranous wings partly supported by an elongated wrist bone (known as the styliform). Although this seemed to be the most plausible interpretation of the evidence, some researchers were naturally skeptical. 2019 gave us another new scansoriopterygid, Ambopteryx, which also preserves wing membranes and a styliform, providing support for the original interpretation of Yi.

Holotype of Ambopteryx, from Wang et al. (2019).

Another phylogenetically recalcitrant clade of maniraptors is the pelagornithids, a group of seagoing Cenozoic birds with tooth-like projections in their beaks. Protodontopteryx from the Waipara Greensand is the oldest known pelagornithid and is known from much of the skeleton, potentially making it very valuable for understanding the origins of these mystery birds. It would get my vote for the most scientifically important new dinosaur of 2019 (though Conflicto would be a close second). Protodontopteryx was much smaller than later pelagornithids (which include the largest known wingspans of any bird at up to 7 m wide), about the size of a typical gull.

Skull of Protodontopteryx, from Mayr et al. (2019).

Last but not least, Carpathiavis from the Oligocene of Poland is a small (sparrow-sized) bird of unclear affinities. It is known from a nearly complete (but poorly preserved) skeleton with some similarities to rail-like birds.

A Small Basal Paravian Not Preserved as Roadkill? Enter Liaoningvenator!

Near the base of Paraves where we once had only Archaeopteryx as a model for the last common ancestor of modern birds and dromaeosaurids, we now know of a plethora of protobirds that likely occupy the same general region of theropod phylogeny. The Late Jurassic Tiaojishan Formation in northeastern China has proven particularly productive in this regard, its fine-grained lake deposits playing host to Pedopenna, Anchiornis, Xiaotingia, Eosinopteryx, and Aurornis, with rumors of more to come.

Many of these early paravians are known from essentially complete remains, have their soft tissues preserved in exquisite detail, and, in the case of Anchiornis, are represented by hundreds of specimens, to the point where their integument, musculature, and even coloration can be restored with unprecedented accuracy. On the flip side, however, these specimens tend to be preserved as flattened corpses similar to roadkill, making aspects of their skeletal anatomy challenging to interpret.

Another geological formation exposed in northeastern China, the Early Cretaceous Yixian Formation, is also known for lake deposits containing "roadkill" fossil specimens with finely-preserved soft tissues. However, the Yixian has other fossil beds that were formed by volcanic ash, and though the fossils found in these generally lack obvious soft tissue structures, they can preserve complete skeletons in three dimensions. A newly-named basal paravian has been recovered from these Yixian ash beds, making it a potentially quite significant find.

The holotype of Liaoningvenator, from Shen et al. (2017).

Liaoningvenator curriei is known from a nearly complete specimen, and at a glance it has some striking features. It looks extremely leggy, with very long lower legs and and feet for its size. Based on rough measurements done in ImageJ, the longest metatarsal is around 64% the length of the tibia, comparable to the ratio seen in some cusorial noasaurids such as Elaphrosaurus. Its forelimbs, conversely, are quite short, the humerus being less than 60% the length of the femur. (Compare Jinfengopteryx, another short-armed basal paravian, in which this figure is around 70%.)

The tail also looks unusually short and the life restoration provided in the paper appears to take this at face value, depicting the preserved length of the tail as its total length in life. The tail as preserved looks truncated, at least to my eye, so I, for one, am skeptical of this interpretation. (The authors do not comment on this issue one way or another.) Even so, it may not be farfetched to suggest that even the complete tail of Liaoningvenator was fairly short, considering that the phylogenetic analysis in the description finds it to be the sister taxon of Eosinopteryx, which has a relatively short tail with only 20 tail vertebrae in total. (For comparison, Anchiornis and Aurornis both have around 30 tail vertebrae.)

Speaking of phylogenetic affinities, the description recovers Liaoningvenator and Eosinopteryx as part of a clade of basal troodontids along with Anchiornis and Xiaotingia. If these findings are valid, Liaoningvenator would be the geologically youngest known member of this basal clade. It would also be the largest member of the group by far: using the Christiansen and Fariña (2004) method of estimating theropod body mass by femur length, Liaoningvenator is predicted to have weighed around 2 kg, whereas its Tiaojishan brethren have all been estimated as less than 1 kg. (On top of that, bone histology indicates that the holotype of Liaoningvenator was still growing at the time of death, though approaching skeletal maturity.)

That's all very fascinating if true. However, the phylogenetic relationships of these basal paravians are notoriously difficult to figure out. Anchiornis (the best-studied Tiaojishan paravian) has bounced between being an avialan, a troodontid, and neither ever since its initial description. In addition, it is not clear whether all of these protobirds really do clade together to the exclusion of other paravians. Perhaps we should also expect a tumultuous phylogenetic future for Liaoningvenator.

Alternative phylogenetic topologies for Paraves recovered by recent studies, based on Shen et al. (2017), Cau et al. (2015), Brusatte et al. (2014), and Foth et al. (2014).

I would be remiss if I neglected to mention that Liaoningvenator is not the only small basal paravian known from a complete, three-dimensionally preserved specimen. Mei is known from two such specimens, also found in ash beds from the Yixian Formation. Infamously, both of these specimens have been preserved in what appears to be a sleeping posture, which has led to jokes that Mei spent all of its time sleeping, despite efforts by paleoartists to depict alternative behaviors. Unlike Liaoningvenator, however, Mei has never been considered a close relative of the Tiaojishan "problem paravians", and is uniformly recovered as a troodontid.

Reference: Shen, C., B. Zhao, C. Gao, J. Lü, and M. Kundrát. 2017. A new troodontid dinosaur (Liaoningvenator curriei gen. et sp. nov.) from the Early Cretaceous Yixian Formation in western Liaoning Province. Acta Geoscientica Sinica 38: 359-371. doi: 10.3975/cagsb.2017.03.06

Natural History Museum of Utah

The welcome reception at this year's SVP took attendees to the Natural History Museum of Utah. The main fossil exhibits are arranged roughly in chronological order, with younger fossils exhibited higher up in the building and older ones closer to the ground floor, threaded throughout by a sloping boardwalk. I consider it to be among the most impressive fossil displays I've visited, in terms of both content and setup.

A juvenile Columbian mammoth.

Megalonyx says, "Hi."

Uintatherium, one of the bizarre mammals of the early Paleogene.

An apparently unnamed dromaeosaurid.

A couple of juvenile Teratophoneus.

The giant alligatoroid Deinosuchus.

A smaller alligatoroid, Brachychampsa.

The large oviraptorosaur Hagryphus, mainly based on Anzu.

The skull of the saurolophine hadrosaur Gryposaurus.

The skull of the lambeosaurine hadrosaur Parasaurolophus.

An ornithomimid referred to Ornithomimus. A sizeable animal considering that we're viewing it from an elevated walkway.

The famous wall of ceratopsians, arranged phylogenetically. From left to right: Styracosaurus, Centrosaurus, Einiosaurus, Pachyrhinosaurus, Achelousaurus, Nasutoceratops, Diabloceratops, Chasmosaurus, Kosmoceratops, Anchiceratops, Triceratops, and Coahuilaceratops.

Off to the side are Protoceratops and Zuniceratops.

Ceratosaurus and Marshosaurus have a disagreement over a Stegosaurus carcass.

The whiplash tail of a mired Barosaurus passes beneath the walkway and arcs high above the heads of visitors. The sauropod is beset by several daring Allosaurus, but somehow this was the only picture I took of the mount. Others have a more representative record.

Size variation in Allosaurus.

The skull of Tanycolagreus, one of the more obscure Morrison theropods.

It was nice to see mounts of Nothronychus and Falcarius, but for unknown reasons I didn't take many good pictures of their heads. Their skulls are largely unknown, in any case.

This model of a troodont with colors lifted directly from Anchiornis was somewhat eyebrow-raising.

A model and mount of Lythronax.

Various arthropods from the Green River Formation.

Crossopholis, a paddlefish from the Green River.

I'd only just gotten out of the fossil exhibit when I received a Facebook message from Meig Dickson telling me that she'd found something in the biology exhibit upstairs that I absolutely had to see. Upon reaching the exhibit, I encountered an interactive tree of life, incredible in its scope and presentation.

However, what Meig had wanted me to see was the image they were using to represent protorosaurs on the interactive phylogeny. Oh, no...

Playing around with the phylogeny some more, we uncovered a number of other oddities. Most unusual was its apparent contention that a genus of extant brown algae is an extinct group of synapsids. Oops.

Hiccups with the interactives aside, the museum was rather impressive in how up to date the displays were. The wall of hominid skulls even includes the recently described Homo naledi.

A phylogeny of corvids.

In the display area for the geologic history of Utah was some more paleo-goodness: Seitaad, a basal sauropodomorph.

I shall conclude this post with the humble Triops, used as an example of species specialized for life in ephemeral desert pools.