Wednesday, January 9, 2019

New (Extinct) Maniraptors of 2018

Now that I can no longer host polls on Blogger, I need a new way to acknowledge the new names in maniraptor paleontology every year (beyond mentioning them in passing during the year end reviews). Why not make myself write a paragraph about each one?

After some thought, I have decided to discuss the new taxa in alphabetical order. That was the way they were listed on the polls, after all. As a bonus, I will now also cover new species of previously-named genera, whereas the polls were focused only on newly-named genera.

Anomalipes zhaoi Yu et al., 2018 (new genus and species)
Meaning of name: Zhao's unusual foot
Location: Wangshi Group, China
Age: Late Cretaceous (Campanian?)

Oviraptorosaurs have generally had a strong showing when it comes to new species lately, often getting two or more new taxa per year, dazzling with spectacularly-preserved holotypes, or both. However, last year gave us just one new species and, truth be told, it's not particularly exciting. Anomalipes is known only from a partial hindlimb. Its describers estimate it to have weighed slightly less than 50 kg, making it larger than average for an oviraptorosaur, but still far from being one of the largest. It was recovered as a caenagnathid in its original description, a result that has been independently corroborated by Andrea Cau.

Archaeopteryx albersdoerferi Kundrát et al., 2018 (new species)
Meaning of name: Albersdörfer's ancient wing
Location: Mörnsheim Formation, Germany
Age: Late Jurassic (Tithonian)

A number of species of Archaeopteryx have been named over the years, but only the type species A. lithographica and sometimes A. siemensii are widely considered to be valid in recent literature. Last year threw a new species into the running. The holotype of A. albersdoerferi has been known to science since the 1990s, nicknamed the eighth or Daiting specimen of Archaeopteryx. However, it had been held in a private collection and was thus unavailable to scientific research until 2009. It comes from slightly younger deposits than the Solnhofen Formation, where the other known specimens of Archaeopteryx were found. Despite being one of the smallest known Archaeopteryx specimens and a late juvenile based on bone histology, the holotype exhibits fusion between some bones of the skull and between the wrist and palm bones, features that aren't seen in other Archaeopteryx specimens. The authors interpret these characteristics as indicators that A. albersdoerferi was more specialized for flight than other Archaeopteryx species.

Ardenna davealleni Tennyson and Mannering, 2018 (new species)
Meaning of name: Dave Allen's shearwater
Location: Ohawe Beach and Waihi Beach, New Zealand
Age: Pliocene (Piacenzian)

The tube-nosed, seafaring petrels are most diverse in the Southern Hemisphere today, but their fossil record in the south is surprisingly scant. The two partial skeletons that have been found of A. davealleni help fill in that void, showing that shearwaters were already present in New Zealand during the Pliocene. A. davealleni is one of the largest shearwaters (comparable to the largest extant species). Anatomically, it resembles the smaller Buller's shearwater, suggesting that it was similarly more specialized for soaring than for underwater flight.

Bannykus wulatensis Xu et al., 2018 (new genus and species)
Meaning of name: Half claw from Wulatehouqi
Location: Bayin-Gobi Formation, China
Age: Early Cretaceous (Aptian)

Bannykus bridges an important gap in our understanding of alvarezsaur evolution, which clearly makes it the most important paleontological discovery in recent history. Not only is it one of the first Early Cretaceous alvarezsaurs to be described, its hands exhibit an intermediate morphology between "typical" theropod hands and the very specialized forelimbs of alvarezsaurids. If I still ran those favorite maniraptor polls, it would be my pick for the best new maniraptor of 2018. I wrote about Bannykus in more detail in a previous blog post.

Skeletal and select elements of Bannykus, from Xu et al. (2018). Preserved bones are shown in gray on the skeletal.

Caihong juji Hu et al., 2018 (new genus and species)
Meaning of name: Big-crested rainbow
Location: Tiaojishan Formation, China
Age: Late Jurassic (Oxfordian)

2018 added another new entry to the persistently increasing list of Anchiornis-like paravians from the Late Jurassic of China. However, the holotype of Caihong is quite spectacular even for a Tiaojishan fossil. It preserves feathers going all the way down to its toes (similar to Anchiornis and Serikornis) and very long tail feathers relative to its body size. Furthermore, analysis of its melanosomes indicates that it had iridescent feathers, especially on its head, neck, and chest. Though not the first Mesozoic maniraptor found to have had iridescent feathers (that honor goes to Microraptor), it is the first known to have the specialized, flattened melanosomes found in some iridescent modern birds. The describers of Caihong also suggest that it had bony crests in front of its eyes, a rarity in paravian theropods. However, some have expressed skepticism of this interpretation, noting that the "crests" might be sideways projections that support a soft tissue brow ridge, which are commonly found in diapsids.

Holotype of Caihong, from Hu et al. (2018).

Chenoanas asiatica Zelenkov et al., 2018 (new species)
Meaning of name: Asiatic duck [named after two extant duck genera, Chenonetta and Anas]
Location: Ööshin Formation, Mongolia and Tunggur Formation, China
Age: Miocene (Serravallian-Tortonian)

Waterfowl appear to have diversified greatly during the Miocene, and last year's findings regarding the genus Chenoanas provided further evidence of that. The recognition of C. asiatica adds a second species of Chenoanas to the Miocene of Central Asia, in addition to the type species C. deserta. The two species differ in details of their humerus (upper arm bone) morphology. The describers of C. asiatica also reassign "Anas" sansaniensis from the Miocene of France and Russia as a third species of Chenoanas, suggesting that this early duck was very geographically widespread. Unlike several other ducks that have been found in the Ööshin Formation, Chenoanas appears to have been more of a dabbler than a diver in its foraging habits.

Cinclosoma elachum Nguyen et al., 2018 (new species)
Meaning of name: Little thrush body
Location: Riversleigh, Australia
Age: Miocene (Burdigalian)

Quail-thrushes are a group of largely terrestrial Australasian passerines. Males are often strikingly colored. Despite their name, they are more closely related to crows than to thrushes. C. elachum is known from various limb bones and represents the oldest known fossil of a quail-thrush. It was smaller than extant quail-thrushes and appears to have lived in a forested environment, supporting previous suggestions that quail-thrushes (which generally live in more open habitats today) had forest-dwelling ancestors.

Ducula tihonireasini Rigal et al., 2018 (new species)
Meaning of name: Tihoni Reasin's imperial pigeon
Location: Gambier Group, French Polynesia (Taravai Island)
Age: Holocene (Meghalayan)

Those who learn of the genus Ducula for the first time are often disappointed to find that the name does not belong to a blood-drinking duck. (Is it strange that I've seen enough people react to the name to be able to comment on how often a specific reaction occurs?) However, the imperial pigeons that actually bear the name are impressive in their own right. These large, tree-dwelling pigeons fly for long distances in search of fruit, making them important seed dispersers in their ecosystems. They are likely responsible for the distribution of many plants on Southeast Asian and Oceanian islands. Large even for an imperial pigeon (though not the largest known species), D. tihonireasini adds further evidence that large body size evolved several times in Ducula. D. tihonireasini may have survived into historic times, given that some 19th Century reports might refer to it.

Eogranivora edentulata Zheng et al., 2018 (new genus and species)
Meaning of name: Toothless early seed-eater
Location: Yixian Formation, China
Age: Early Cretaceous (Barremian-Aptian)

Originally mistaken for a specimen of Hongshanornis, the holotype of Eogranivora turned out to be quite a different theropod with its lack of teeth and stocky hindlimbs. It represents the earliest known euornithine preserved with direct evidence of seed-eating. I wrote about Eogranivora in more detail in a previous blog post.

Holotype of Eogranivora, from Zheng et al., (2018).

Gettyia gloriae (Varricchio and Chiappe, 1995), revised by Atterholt et al., 2018 (new genus)
Meaning of name: Named after Gloria Siebrecht and Mike Getty
Location: Two Medicine Formation, U.S.A.
Age: Late Cretaceous (Campanian)

Previously considered a species of Avisaurus, Gettyia was given its own genus when it was found to be more closely related to the newly-described Mirarce (covered below) than to the type species of Avisaurus (A. archibaldi). Gettyia appears to have been much smaller than the eagle-sized Avisaurus, measuring less than half its size in linear measurements, though both taxa are known only from feet.

Jinguofortis perplexus Wang et al., 2018 (new genus and species)
Meaning of name: Perplexing brave female warrior
Location: Dabeigou Formation, China
Age: Early Cretaceous (Barremian)

Jinguofortis adds to the ever-growing aviary of the Jehol Biota. It had several features indicative of refined flapping ability, including a reduced third finger, a curved third metacarpal (palm bone), and a well-developed ridge on the humerus. The wing feathers of the holotype are well preserved and suggest that it was capable of maneuverable flight. However, it also had characteristics more typical of non-avialan theropods, such as fusion between the scapula and coracoid bones in the shoulder girdle. The phylogenetic analysis in its original description found Jinguofortis to be a close relative of Chongmingia, an enigmatic avialan known from less complete remains. The clade uniting the two (Jinguofortisidae) was in turn found to be fairly closely related to ornithothoracines (enantiornithines and euornithines).

Holotype of Jinguofortis, from Wang et al. (2018).

Kischinskinia scandens Volkova and Zelenkov, 2018 (new genus and species)
Meaning of name: Climbing, named after A. A. Kishchinsky
Location: Olkhon Island, Russia
Age: Miocene (Burdigalian-Langhian)

Despite accounting for about 60% of living bird diversity, passerines are poorly known in the fossil record. As such, we have little fossil evidence of their presumably dramatic evolutionary diversification. Kischinskinia is thus significant in being the oldest known oscine passerine (songbird) from Asia. It is only known from partial hindlimb bones, but enough has been found to suggest that it was a certhioid songbird, making it a close relative of nuthaches, treecreepers, and wrens. Like many living certhioids, it likely foraged by creeping along vertical surfaces. Its early Miocene age is consistent with some recent molecular clock estimates for the divergence times of major songbird lineages and their dispersal out of Australia.

Litorallus livezeyi Mather et al., 2018 (new genus and species)
Meaning of name: Livezey's shore rail
Location: Bannockburn Formation, New Zealand
Age: Miocene (Burdigalian)

Rails are well known (at least in the ornithological community) for their ability to colonize remote islands and tendency to evolve flightlessness. Holocene rails alone are known to have evolved flightlessness over thirty different times. Litorallus (along with Priscaweka, discussed below) shows that this phenomenon has been occurring as far back as the Miocene. This is evidenced by the fact that its lower arm was less than 30% the length of its shin, whereas this value ranges 45-65% in extant flying rails.

Mirarce eatoni Atterholt et al., 2018 (new genus and species)
Meaning of name: Eaton's wonderful winged messenger [named after Arce, winged messenger of the Titans in Greek mythology]
Location: Kaiparowits Formation, U.S.A.
Age: Late Cretaceous (Campanian)

Enantiornithines ("opposite birds") were not recognized as a group until the 1980s, but have since turned out to have been the most diverse lineage of avialans during the Mesozoic. Numerous complete specimens of enantiornithines are now known, the majority coming from the Early Cretaceous Jehol Biota in China. Although these fossils often include stunning preservation of soft tissues such as feathers, they also tend to be preserved as flat slabs, obscuring details of skeletal anatomy. The holotype of Mirarce, on the other hand, is known from bones preserved in three dimensions, and it is the most completely known North American enantiornithine to boot. It appears to have been a close relative of Gettyia (discussed above) and Avisaurus, potentially shedding light on the anatomy of these taxa (which are only known from feet). Mirarce was convergent on modern birds in that it had a narrow wishbone and a deep keel on the breastbone, providing further evidence for parallel evolution of refined flight abilities in avialans. It is also the first enantiornithine found with quill knobs, bony attachment points for wing feathers on the lower arm. Though large for an enantiornithine, Mirarce was not quite as big as Avisaurus.

Skeletal of Mirarce, from Atterholt et al. (2018). Preserved elements are shown in white. Scott Hartman, the illustrator of the skeletal, has noted that the (unknown) skull was depicted as toothless because the describers of Mirarce speculate that toothlessness was common in Late Cretaceous enantiornithines. Personally, I don't think we have enough information to draw that inference.

Muriwaimanu tuatahi (Jones et al. in Slack et al., 2006), revised by Mayr et al., 2018 (new genus)
Meaning of name: First after Waimanu
Location: Waipara Greensand, New Zealand
Age: Paleocene (Selandian)

Muriwaimanu was originally described as a second species of Waimanu, but a study last year noted that a sister group relationship between the two is not strongly supported and gave it its own genus. Only slightly younger than W. manneringi (the type species of Waimanu) in terms of geologic age, Muriwaimanu is among the oldest stem-penguins. Several partial skeletons of this early waterbird have been described, making it one of the most completely known Paleocene penguins.

Orienantius ritteri Li et al., 2018 (new genus and species)
Meaning of name: Ritter's dawn enantiornithine
Location: Huajiying Formation, China
Age: Early Cretaceous (Hauterivian)

Orienantius is the latest in a long list of enantiornithines that have been described from the Jehol Biota (as mentioned under the entry for Mirarce), but the two known specimens are spectacular even for Jehol fossils. They preserve not only feathers, but also the skin membranes surrounding the wings, muscles on the hindlimbs, and pads on the bottoms of their toes. Its wing anatomy suggests that it alternated between flapping and gliding in flight like many small birds today, and was capable of flying with great agility to navigate its forest enivironment.

Holotype of Orienantius, from Li et al. (2018).

Pandion pannonicus Kessler, 2018 (new species)
Meaning of name: From Pannonia, named after Pandion II of Greek mythology
Location: Máriahalom, Hungary
Age: Oligocene (Chattian)

This is one of the oldest known osprey species; the only records that are older come from the early Oligocene of Egypt. P. pannonicus is only known from a claw, but osprey claws are very distinctive. It was smaller than other known ospreys, including the extant species.

Panraogallus hezhengensis Li et al., 2018 (new genus and species)
Meaning of name: Coiling chicken from Hezheng
Location: Liushu Formation, China
Age: Miocene (Tortonian)

This pheasant is known from a well-preserved, nearly complete skeleton. That on its own is a rarity for bird fossils and would have made it a notable discovery. However, its main claim to fame is that it preserves a very elongate windpipe (likely longer than its own body) that would have been coiled up in its chest cavity in life. This unusual feature is also known to have independently evolved in some extant galliforms (including some curassows, guineafowl, and grouse) as well as other birds such as cranes. These birds use their elongate windpipes to produce particularly loud or low-frequency calls, suggesting that Panraogallus did the same.

Holotype of Panraogallus, from Li et al. (2018).

Priscaweka parvales Mather et al., 2018 (new genus and species)
Meaning of name: Small-winged ancient weka
Location: Bannockburn Formation, New Zealand
Age: Miocene (Burdigalian)

Priscaweka was a second flightless rail that lived alongside Litorallus (discussed above). It was smaller (about the size of the recently extinct Chatham rail) and apparently more abundant than Litorallus. Specimens of Priscaweka appear to come in two clusters of size ranges, suggesting sexual dimorphism. If so, it appears that males of this taxon were slightly larger than females, similar to most extant rails.

Proardea(?) deschutteri Mayr et al., 2018 (new species)
Meaning of name: De Schutter's before Ardea
Location: Borgloon Formation, Belgium
Age: Oligocene (Rupelian)

P. deschutteri is only known from a partial foot, but it is notable in that it's one of the earliest known herons. It was a small heron, about the same size as the squacco heron. Its describers note that its assignment to Proardea is tentative.

Qiupanykus zhangi Lü et al., 2018 (new genus and species)
Meaning of name: Zhang's Qiupa claw
Location: Qiupa Formation, China
Age: Late Cretaceous (Maastrichtian?)

2018 was a good year for alvarezsaurs, seeing the description of three new species. Qiupanykus is known from a poorly-preserved partial skeleton that seems pretty anatomically standard for an alvarezsaurid, but it did receive some press for the suggestion that it provided evidence for egg-eating in alvarezsaurs. This would have made it significant for understanding alvarezsaurid paleobiology if true, but unfortunately the evidence is extremely unconvincing (as also noted by Andrea Cau), consisting entirely of the fact that an oviraptorosaur eggshell fragment was preserved near the holotype. That is flimsier reasoning than the assumption that the holotype of Oviraptor was preserved in the middle of raiding a nest; it's at least likely that Oviraptor was interacting with the eggs it was preserved with before it died! Tragically, Qiupanykus was to my knowledge the last maniraptor that Junchang Lü (known for his research on oviraptorosaurs and pterosaurs) described as first author prior to his untimely passing in October 2018.

Rallus gracilipes Takano and Steadman, 2018 (new species)
Meaning of name: Slender-footed rail
Location: Sawmill Sink, the Bahamas (Great Abaco Island)
Age: Pleistocene (Late Pleistocene)

R. gracilipes was another flightless rail species described in 2018, but as a Pleistocene bird it was much younger than Litorallus and Priscaweka (both discussed above). It is known from bones of both the front and hind limbs, and so far is not known to have survived into the Holocene.

Romainvillia kazakhstanensis Zelenkov, 2018 (new species)
Meaning of name: From Kazakhstan, named after Romainville
Location: Kustovskaya Formation, Kazakhstan
Age: Eocene (Priabonian)

Romainvillia is one of the oldest known anseriforms that was likely closely related to anatids (true ducks and geese). Previously known from the Eocene-Oligocene of Europe, R. kazakhstanensis (known from a coracoid) shows that its range extended into Asia as well.

Sequiwaimanu rosieae Mayr et al., 2018 (new genus and species)
Meaning of name: Rosie's following Waimanu
Location: Waipara Greensand, New Zealand
Age: Paleocene (Selandian)

Sequiwaimanu was slightly younger than Muriwaimanu and Waimanu and may have been slightly more closely related to modern penguins, but it is still one of the oldest known stem-penguins. Perhaps more notably, the holotype is the most complete and best-preserved single specimen of any Paleocene penguin found; only its foot remains largely unknown. Like Muriwaimanu, Sequiwaimanu had a spear-like beak and less stiffened flippers compared to extant penguins.

Skull of Sequiwaimanu, from Mayr et al. (2018).

Vanellus liffyae De Pietri et al., 2018 (new species)
Meaning of name: Liffy's lapwing
Location: Tirari Formation, Australia
Age: Pliocene (Piacenzian)

Lapwings are a group of often boldly-colored plovers known for fiercely defending their nests. Facilitating this behavior are the large spurs found on the wrists of many species, including the two that live in Australia today, the banded and masked lapwings. Known from a coracoid, V. liffyae was likely a close relative of these two species, showing that this group of lapwings had colonized Australia by the late Pliocene.

Vorombe titan (Andrews, 1894), revised by Hansford and Turvey, 2018 (new genus)
Meaning of name: Giant big bird
Location: Itampolo, Madagascar
Age: Pleistocene-Holocene (Late Pleistocene-Meghalayan)

The taxonomy of the recently extinct elephant birds from Madagascar have long been controversial. A study last year used a morphometric approach to identify distinct elephant bird species and concluded that only four species were valid: Aepyornis maximus, Aepyornis hildebrandti, Mullerornis modestus, and "Aepyornis" titan (long lumped into A. maximus). The authors consider "A." titan to be distinct enough from Aepyornis to warrant a new genus, Vorombe. Vorombe was the largest elephant bird; the biggest specimens included in the study were estimated at body masses of over 730 kg. An incomplete femur hints that it may have gotten even larger (up to 860 kg). This would make Vorombe the largest paravian known and comparable in size to the smallest adult sauropods (such as Magyarosaurus). Imagine that: the largest known paravian was a recently extinct neornithine bird, a group of theropods notable for their trend in decreasing body size throughout their evolutionary history.

Winnicavis gorskii Bochenski et al., 2018 (new genus and species)
Meaning of name: Górski's Winnica bird
Location: Menilite Formation, Poland
Age: Oligocene (Rupelian)

Another addition to the scant fossil record of passerines, Winnicavis was a small bird (about the size of a great tit) known from articulated wing and leg bones. Several other early passerines have been previously described from the early Oligocene of Europe, but determining their relationships to living passerine groups has proven challenging.

Xiyunykus pengi Xu et al., 2018 (new genus and species)
Meaning of name: Peng's western region claw
Location: Tugulu Group, China
Age: Early Cretaceous (Barremian-Aptian)

The third new alvarezsaur of 2018, Xiyunykus sheds light on the previously unknown Early Cretaceous history of alvarezsaurs along with Bannykus. Unfortunately, a complete forelimb is not known, but what is preserved shows that it likely had an intermediate morphology between Bannykus and "typical" theropods. I wrote about Xiyunykus in more detail in a previous blog post.

Yangavis confucii Wang and Zhou, 2018 (new genus and species)
Meaning of name: Confucius [and] Yang's bird
Location: Yixian Formation, China
Age: Early Cretaceous (Barremian-Aptian)

Another new species from the Jehol Biota, this confuciusornithiform is known from a nearly complete skeleton, but this time not preserved with any feathers. Yangavis had relatively longer forelimbs and an unreduced claw on the second finger compared to other confuciusornithiforms, though the functional significance of these features has not been rigorously assessed.

Zygodactylus grandei Smith et al., 2018 (new species)
Meaning of name: Grande's paired toes
Location: Green River Formation, U.S.A.
Age: Eocene (Ypresian)

Zygodactylids were a group of small birds from the Eocene-Miocene of Europe and North America. Some authors considered them close relatives of woodpeckers due to their zygodactyl feet (with the first and fourth toes both pointing backward), but more recent studies favor a closer relationship with passerines, which makes sense in light of the fact that molecular evidence indicates that the closest living relatives of passerines are the also zygodactyl parrots. Known from a well-preserved skeleton, Z. grandei is the oldest known species of Zygodactylus and the first to be described from North America. The phylogenetic analysis in its description finds it to be a close relative of Eozygodactylus. Though the authors refrain from making major taxonomic changes to zygodactylids, this opens up the possibility that Eozygodactylus will be considered a species of Zygodactylus in future revisions. Coincidentally, the first new dinosaur of 2019 appears to be another new species of Zygodactylus.

Holotype of Z. grandei, from Smith et al. (2018).

Writing this post turned out to be moderately time consuming, so let me know if you'd be interested in seeing posts like this one in future years. I do have ideas to help reduce the workload should I make it a new annual tradition.

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