Oculudentavis khaungraae gen. et sp. nov. (1 Viewer)

[Fred Ruhe]

Lida Xing, Jingmai K. O’Connor, Lars Schmitz, Luis M. Chiappe, Ryan C. McKellar, Qiru Yi & Gang Li, 2020

Hummingbird-sized dinosaur from the Cretaceous period of Myanmar

Nature volume 579, pages245–249

Abstract: https://www.nature.com/articles/s41586-020-2068-4

Skeletal inclusions in approximately 99-million-year-old amber from northern Myanmar provide unprecedented insights into the soft tissue and skeletal anatomy of minute fauna, which are not typically preserved in other depositional environments. Among a diversity of vertebrates, seven specimens that preserve the skeletal remains of enantiornithine birds have previously been described all of which (including at least one seemingly mature specimen) are smaller than specimens recovered from lithic materials. Here we describe an exceptionally well-preserved and diminutive bird-like skull that documents a new species, which we name Oculudentavis khaungraae gen. et sp. nov. The find appears to represent the smallest known dinosaur of the Mesozoic era, rivalling the bee hummingbird (Mellisuga helenae)—the smallest living bird—in size. The O. khaungraae specimen preserves features that hint at miniaturization constraints, including a unique pattern of cranial fusion and an autapomorphic ocular morphology that resembles the eyes of lizards. The conically arranged scleral ossicles define a small pupil, indicative of diurnal activity. Miniaturization most commonly arises in isolated environments, and the diminutive size of Oculudentavis is therefore consistent with previous suggestions that this amber formed on an island within the Trans-Tethyan arc. The size and morphology of this species suggest a previously unknown bauplan, and a previously undetected ecology. This discovery highlights the potential of amber deposits to reveal the lowest limits of vertebrate body size.

Enjoy,

Fred

 

[Fred Ruhe]

News and blogs:

Tiny bird fossil might be the worldâs smallest dinosaur

https://www.nature.com/articles/d41586-020-00576-6

http://tetzoo.com/blog/2020/3/10/hummingbird-sized-archaic-birds-of-cretaceous

https://www.scientificamerican.com/article/smallest-known-dinosaur-found-in-amber/

https://www.sciencemag.org/news/2020/03/head-tiny-dinosaur-found-trapped-amber

https://www.nationalgeographic.com/...-ever-fossil-dinosaur-found-trapped-in-amber/

https://cosmosmagazine.com/palaeontology/tiny-bird-like-dinosaur-smallest-ever-found

https://www.livescience.com/smallest-dinosaur-of-mesozoic.html

Nature Podcast:

First news story at 0:44 with Jingmai O'Connor

https://www.nature.com/articles/d41586-020-00723-z

This miniature skull belonged to a 2-gram dinosaur
The 100-million-year-old animal might have been the smallest dinosaur.

https://www.nature.com/articles/d41586-020-00668-3


Fred

 

[Fred Ruhe]

Systematic palaeontology

Aves, Linnaeus 1758

Oculudentavis khaungraae gen. et sp. nov.

Holotype. Hupoge Amber Museum (HPG)-15-3, a complete skull preserved in amber; the block measures 31.5 mm × 19.5 mm × 8.5 mm and weighs 2.84 g.

Etymology. The generic name Oculudentavis is derived from the Latin oculus (eye), dentes (teeth) and avis (bird). The species name khaungraae is from Khaung Ra, who donated the specimen to the Hupoge Amber Museum.

Locality and horizon. Cenomanian age, 98.8 ± 0.6 million years ago. Angbamo site, Tanai township (Myitkyina district, Hukawng valley, Kachin province), northern Myanmar.

Fred


Photograph, computed tomography scans and interpretive drawings of the HPG-15-3 holotype of O. khaungraae. a, Photograph of the amber piece with skull ventrolaterally exposed. b, c, Scan (b) and drawing (c), left lateral view. d, e, Scan (d) and drawing (e), rostral view. f, g, Scan (f) and drawing (g), occipital view. h, i, Scan (h) and drawing (i), dorsal view. de, dentary; fr, frontal; hy, hyoid bone (or bones); jg, jugal; la, lacrimal; mx, maxilla; pa, parietal; pm, premaxilla; po, postorbital; qd, quadrate; sc, scleral ossicle; so, supraoccipital; sq, squamosal; th, teeth. Scale bars, 5 mm; longer scale bar below b applies to b−i.

 

[l_raty]

A dissenting view on the classification as a basal bird: https://pterosaurheresies.wordpress...d-or-dinosaur-its-a-tiny-cosesaur-lepidosaur/

 

[Fred Ruhe]

A dissenting view on the classification as a basal bird: https://pterosaurheresies.wordpress...d-or-dinosaur-its-a-tiny-cosesaur-lepidosaur/

The authors write:

"The skull of O. khaungraae reveals a general avian morphology, including a slender, tapering rostrum with retracted naris, an enlarged and well-defined eye socket, a short compressed postorbital region and a dome-shaped skull roof. O. khaungraae appears to represent the smallest known Mesozoic dinosaur, rivalling the extant bee hummingbird—the smallest known dinosaur of all time—in size."

That is the reason they place it in Aves, but they have doubts.

Fred

 

[albertonykus]

A dissenting view on the classification as a basal bird: https://pterosaurheresies.wordpress...d-or-dinosaur-its-a-tiny-cosesaur-lepidosaur/

Pterosaur Heresies is not considered a particularly credible website, to say the least. Please see this article by vertebrate paleontologist Darren Naish. (Linking through Wayback Machine because the latest version of Scientific American has removed the images.)

That being said, many working paleontologists have also expressed skepticism of dinosaurian affinities for this animal on social media. The most thorough coverage that I've seen so far is by Andrea Cau (a translate button is available for those who don't read Italian).

 

[Mysticete]

To be fair, there are a lot of folks who think this might be a lepidosaur who aren't Peters. Check out Darren Naishs recent blog.

http://tetzoo.com/blog/2020/3/10/hu...SprUVb6cKi2UesNKGXinZbFb1WVmMC3lpOiyCrgfK9nJQ

Not to mention that whole "maybe we shouldn't be formerly describing new taxa collected by effectively slave labor" issue.

 

[albertonykus]

... Yes, I mentioned the presence of other skeptics and linked to a relevant article in my post.

The conditions under which these Burmese amber finds are procured should absolutely be of foremost concern. Mark Witton's recent post about the situation is worth a read.

 

[Fred Ruhe]

Controversies about the specimen
Ethics of using conflict amber:
The ugly truth behind Oculudentavis

https://markwitton-com.blogspot.com/2020/03/the-ugly-truth-behind-oculudentavis.html

Some Paleontologists Seek Halt to Myanmar Amber Fossil Research

https://www.nytimes.com/2020/03/11/science/amber-myanmar-paleontologists.html

A number of websites, blogs, and twitter feeds are proposing that Oculudentavis is not an avian theropod but some kind of lepidosaur or even a late megalancosaur

Oculudentavis is not a theropod

http://theropoddatabase.blogspot.com/2020/03/oculudentavis-is-not-theropod.html

Update to TetZoo post:

http://tetzoo.com/blog/2020/3/10/hummingbird-sized-archaic-birds-of-cretaceous

https://whyevolutionistrue.wordpres...-on-the-tiny-dino-bird-i-described-yesterday/

Fred

 

[l_raty]

Li Z, Wang W, Hu H, Wang M, Yi M, Lu J. Is Oculudentavis a bird or even archosaur?
BioRxiv preprint: https://doi.org/10.1101/2020.03.16.993949

 

[Fred Ruhe]

Li Z, Wang W, Hu H, Wang M, Yi M, Lu J. Is Oculudentavis a bird or even archosaur?
BioRxiv preprint: https://doi.org/10.1101/2020.03.16.993949

Wang Wei and others have posted an online article in Chinese to critique the identification of the fossil skull as that of a "bird." They join others (notably Andrea Cau) in pointing out the lizard-like features and problems with the methods and analysis used to conclude that the creature was a tiny avian dinosaur.

This "article" has been posted as a news story and I'm not sure if IVPP will provide an official English translation in the near future. Google Translate does an OK job of translating the text, but some of the terminology gets slightly garbled. Note that the term "wulong" [black dragon] in Chinese can mean an "unexpected mistake." It is also the name for "oolong" tea, which is what Google Translate gives. The 'wu' character can mean a "crow" as well,Âso there may be a bit of a pun intended (wulong 'crow dragon') in the Chinese article title on the possible misidentification of the fossil as a bird.

Wang Wei, Zhiheng Li,Hu Yan, Wang Min, Hongyu Yi & Lu Jing (2020)
The "smallest dinosaur in history" in amber may be the biggest mistake in history.
Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences: Popular Science News (2020/03/13)
http://ivpp.cas.cn/kxcb/kpdt/202003/t20200313_5514594.html

**

Online English news item translation summary (with a few mistranslations):

https://www.tellerreport.com/life/2...d-to-progress-in-discussion"-.rye6DnoOS8.html

==========

Here is the list of problems found by the authors:

Doubts 1. Can the shape of the head prove that it is a bird?
Doubt 2. Unreasonable Phylogenetic Analysis
Doubt 3. Birds without antorbital fenestrae?
Doubt 4. "Birds" with pleurodont teeth?
Doubt 5. Mysterious quadratojugal bone
Doubt 6. Scleral bones only found in lizards
Doubt 7. The bird with the most teeth in history?
Doubt 8. Body size
Doubt 9. No feathers?
Doubt 10. Strange wording and logic chains

******

From the text:

We hope that the authors of the paper will respond publicly to these questions as soon as possible. At the same time, it is hoped that the authors of the paper will quickly release the raw data of CT scans, so that other scientists can verify the existing results based on the raw data.

However, in the absence of reliable evidence, the authors of the cover paper in "Nature" identified an amber skull with a large number of lizard identification characteristics as a dinosaur/bird very arbitrarily. The importance and scientific significance of the interpretation cannot be discussed.


After Ben Creisler (DINOSAUR Mailing List) http://dml.cmnh.org/2020Mar/msg00074.html

Fred

 

[Fred Ruhe]

An update (in Chinese):

==

Oculudentavis controversy, possible retraction of Nature paper...

Authors of original Oculudentavis "tiniest dinosaur" paper may be considering a retraction. The bioRxv preprint paper has been submitted to Nature with the consent of the corresponding author of the original paper.


http://www.uua.cn/show-8-10299-1.html

***
The China Science News was informed that the above 6 paleontologists recently obtained high-resolution CT scan data provided by Li Gang (one of the original authors), a researcher at the Institute of High Energy Physics, Chinese Academy of Sciences.

After reanalyzing the scan data, it was found that various morphological evidences indicate that the phylogenetic position of Oculudentavis and dinosaurs/birds are highly contradictory, but closer to that of the lizards.

The CT scan data proved that Oculudentavis does not have a square jugal bone, which is exactly the characteristic of the lizard.


Weibo sources said that six doubters had contacted the corresponding author of the original paper for the first time, and the latter had considered retracting the manuscript with Nature Magazine. At the same time, several international research groups are currently submitting questions to the Oculudentavis papers to major journals and preprint platforms.

===

On Thu, Mar 19, 2020 at 8:58 AM Ben Creisler <[email protected]> wrote:


The same authors have now posted a more formal preprint (without peer review) article with their analysis in English:



Zhiheng Li, Wei Wang, Han Hu, Min Wang, Hongyu Yi & Jing Lu (2020)
Is Oculudentavis a bird or even archosaur?
bioRxiv (preprint)
doi: https://doi.org/10.1101/2020.03.16.993949
https://www.biorxiv.org/content/10.1101/2020.03.16.993949v1


Free pdf:
https://www.biorxiv.org/content/10.1101/2020.03.16.993949v1.full.pdf


Recent finding of a fossil, Oculudentavis khaungraae Xing et al. 2020, entombed in a Late Cretaceous amber was claimed to represent a humming bird-sized dinosaur. Regardless the intriguing evolutional hypotheses about the bauplan of Mesozoic dinosaurs (including birds) posited therein, this enigmatic animal, however, demonstrates various lizard-like morphologies, which challenge the fundamental morphological gap between Lepidosauria and Archosauria. Here we reanalyze the original computed tomography scan data of Oculudentavis. A suit of squamate synapomorphies, including pleurodont marginal teeth and an open lower temporal fenestra, overwhelmingly support its squamate affinity, and that the avian or dinosaurian assignment of Oculudentavis is conclusively rejected.

On Sat, Mar 14, 2020 at 10:25 AM Ben Creisler <[email protected]> wrote:


Ben Creisler

[email protected]




Wang Wei and others have posted an online article in Chinese to critique the identification of the fossil skull as that of Âa "bird." They join others (notably Andrea Cau) in pointing out the lizard-like features and problems with the methods and analysis used to conclude that the creature was a tiny avian dinosaur.Â


This "article" has been posted as a news story and I'm not sure if IVPP will provide an official English translation in the near future. Google Translate does an OK job of translating the text, but some of the terminology gets slightly garbled. Note that the term "wulong" [black dragon] in Chinese can mean an "unexpected mistake." It is also the name for "oolong" tea, which is what Google Translate gives. The 'wu' character can mean a "crow" as well,Âso there may be a bit of a pun intended (wulong 'crow dragon') in the Chinese article title on the possible misidentification of the fossil as a bird.


**


Wang Wei, Zhiheng Li,Hu Yan, Wang Min, Hongyu Yi & Lu Jing (2020)
The "smallest dinosaur in history" in amber may be the biggest mistake in history.
Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences: Popular Science News (2020/03/13)
http://ivpp.cas.cn/kxcb/kpdt/202003/t20200313_5514594.html


**
Online English news item translation summary (with a few mistranslations):


https://www.tellerreport.com/life/2...d-to-progress-in-discussion"-.rye6DnoOS8.html

==========


Here is the list of problems found by the authors:


Doubts 1. Can the shape of the head prove that it is a bird?
Doubt 2. Unreasonable Phylogenetic Analysis
Doubt 3. Birds without antorbital fenestrae?
Doubt 4. "Birds" with pleurodont teeth?
Doubt 5. Mysterious quadratojugal bone
Doubt 6. Scleral bones only found in lizards
Doubt 7. The bird with the most teeth in history?
Doubt 8. Body size
Doubt 9. No feathers?
Doubt 10. Strange wording and logic chains

******

From the text:

We hope that the authors of the paper will respond publicly to these questions as soon as possible. At the same time, it is hoped that the authors of the paper will quickly release the raw data of CT scans, so that other scientists can verify the existing results based on the raw data.


However, in the absence of reliable evidence, the authors of the cover paper in "Nature" identified an amber skull with a large number of lizard identification characteristics as a dinosaur/bird very arbitrarily. The importance and scientific significance of the interpretation cannot be discussed.Â


===

Fred

 

[Fred Ruhe]

Ooops... Make that quadratojugal for "square jugal" in Chinese...Â




On Sat, Mar 21, 2020 at 9:30 AM Ben Creisler <[email protected]> wrote:



An update (in Chinese):



==


Oculudentavis controversy, possible retraction of Nature paper...





Authors of original Oculudentavis "tiniest dinosaur" paper may be considering a retraction. The bioRxv preprint paper has been submitted to Nature with the consent of the corresponding author of the original paper.


http://www.uua.cn/show-8-10299-1.html

***
The China Science News was informed that the above 6 paleontologists recently obtained high-resolution CT scan data provided by Li Gang (one of the original authors), a researcher at the Institute of High Energy Physics, Chinese Academy of Sciences.
Â
After reanalyzing the scan data, it was found that various morphological evidences indicate that the phylogenetic position of Oculudentavis and dinosaurs/birds are highly contradictory, but closer to that of the lizards.

The CT scan data proved that Oculudentavis does not have a quadratojugal bone, which is exactly the characteristic of the lizard.


Weibo sources said that six doubters had contacted the corresponding author of the original paper for the first time, and the latter had considered retracting the manuscript with Nature Magazine. At the same time, several international research groups are currently submitting questions to the Oculudentavis papers to major journals and preprint platforms.

===




On Thu, Mar 19, 2020 at 8:58 AM Ben Creisler <[email protected]> wrote:




The same authors have now posted a more formal preprint (without peer review) article with their analysis in English:



Zhiheng Li, Wei Wang, Han Hu, Min Wang, Hongyu Yi & Jing Lu (2020)
Is Oculudentavis a bird or even archosaur?
bioRxiv (preprint)
doi: https://doi.org/10.1101/2020.03.16.993949
https://www.biorxiv.org/content/10.1101/2020.03.16.993949v1


Free pdf:
https://www.biorxiv.org/content/10.1101/2020.03.16.993949v1.full.pdf








Recent finding of a fossil, Oculudentavis khaungraae Xing et al. 2020, entombed in a Late Cretaceous amber was claimed to represent a humming bird-sized dinosaur. Regardless the intriguing evolutional hypotheses about the bauplan of Mesozoic dinosaurs (including birds) posited therein, this enigmatic animal, however, demonstrates various lizard-like morphologies, which challenge the fundamental morphological gap between Lepidosauria and Archosauria. Here we reanalyze the original computed tomography scan data of Oculudentavis. A suit of squamate synapomorphies, including pleurodont marginal teeth and an open lower temporal fenestra, overwhelmingly support its squamate affinity, and that the avian or dinosaurian assignment of Oculudentavis is conclusively rejected.







On Sat, Mar 14, 2020 at 10:25 AM Ben Creisler <[email protected]> wrote:







Ben Creisler

[email protected]




Wang Wei and others have posted an online article in Chinese to critique the identification of the fossil skull as that of Âa "bird." They join others (notably Andrea Cau) in pointing out the lizard-like features and problems with the methods and analysis used to conclude that the creature was a tiny avian dinosaur.Â







This "article" has been posted as a news story and I'm not sure if IVPP will provide an official English translation in the near future. Google Translate does an OK job of translating the text, but some of the terminology gets slightly garbled. Note that the term "wulong" [black dragon] in Chinese can mean an "unexpected mistake." It is also the name for "oolong" tea, which is what Google Translate gives. The 'wu' character can mean a "crow" as well,Âso there may be a bit of a pun intended (wulong 'crow dragon') in the Chinese article title on the possible misidentification of the fossil as a bird.


**


Wang Wei, Zhiheng Li,Hu Yan, Wang Min, Hongyu Yi & Lu Jing (2020)
The "smallest dinosaur in history" in amber may be the biggest mistake in history.
Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences: Popular Science News (2020/03/13)
http://ivpp.cas.cn/kxcb/kpdt/202003/t20200313_5514594.html


**
Online English news item translation summary (with a few mistranslations):


https://www.tellerreport.com/life/2...d-to-progress-in-discussion"-.rye6DnoOS8.html

==========


Here is the list of problems found by the authors:


Doubts 1. Can the shape of the head prove that it is a bird?
Doubt 2. Unreasonable Phylogenetic Analysis
Doubt 3. Birds without antorbital fenestrae?
Doubt 4. "Birds" with pleurodont teeth?
Doubt 5. Mysterious quadratojugal bone
Doubt 6. Scleral bones only found in lizards
Doubt 7. The bird with the most teeth in history?
Doubt 8. Body size
Doubt 9. No feathers?
Doubt 10. Strange wording and logic chains
******




From the text:


We hope that the authors of the paper will respond publicly to these questions as soon as possible. At the same time, it is hoped that the authors of the paper will quickly release the raw data of CT scans, so that other scientists can verify the existing results based on the raw data.


However, in the absence of reliable evidence, the authors of the cover paper in "Nature" identified an amber skull with a large number of lizard identification characteristics as a dinosaur/bird very arbitrarily. The importance and scientific significance of the interpretation cannot be discussed.Â


===

Fred

 

[Fred Ruhe]

There is now a reply in bioRxiv from the authors of the original description:

Jingmai O'Connor, Lida Xing, Luis Chiappe, Lars Schmitz, Ryan McKellar, Gang Li & Qiru Yi (2020)

Reply to Li et al. "Is Oculudentavis a bird or even archosaur?"

bioRxiv 2020.06.12.147041 (preprint)
doi: https://doi.org/10.1101/2020.06.12.147041
https://www.biorxiv.org/content/10.1101/2020.06.12.147041v1

Free pdf:
https://www.biorxiv.org/content/10.1101/2020.06.12.147041v1.full.pdf

We welcome any new interpretation or alternative hypothesis regarding the taxonomic affinity of the enigmatic Oculudentavis khaungraae. However, here we demonstrate that Li et al. have failed to provide conclusive evidence for the reidentification of HPG-15-3 as a squamate. We analyse this specimen in a matrix that includes a broad sample of diapsid reptiles and resolve support for this identification only when no avian taxa are included. Regardless of whether this peculiar skull belongs to a tiny bird or to a bizarre new group of lizards, the holotype of Oculudentavis khaungraae is a very interesting and unusual specimen, the discovery of which represents an important contribution to palaeontology. Its discovery documents a potential new case of convergent evolution in reptiles, while highlighting the importance of amber deposits for documenting taxa not recorded in sedimentary deposits.

******

Also, the bioRxiv preprint of the Li et al. paper has been revised since originally posted

Revision history:

https://www.biorxiv.org/content/10.1101/2020.03.16.993949v4.article-info

https://www.biorxiv.org/content/10.1101/2020.03.16.993949v4

Fred

 

[albertonykus]

Further developments...

Xing, L., J.K. O’Connor, L. Schmitz, L.M. Chiappe, R.C. McKellar, Q. Yi, and G. Li (2020)
Retraction Note: Hummingbird-sized dinosaur from the Cretaceous period of Myanmar
https://www.nature.com/articles/s41586-020-2553-9

We, the authors, are retracting this Article to prevent inaccurate information from remaining in the literature. Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis regarding the phylogenetic position of HPG-15-3.

 

[albertonykus]

New preprint:

Bolet, A., E.L. Stanley, J.D. Daza, J.S. Arias, A. Cernansky, M. Vidal-Garcia, A.M. Bauer, J.J. Bevitt, A. Peretti, and S.E. Evans (2020)
The tiny Cretaceous stem-bird Oculudentavis revealed as a bizarre lizard
bioRxiv 2020.08.09.243048
doi: 10.1101/2020.08.09.243048
https://www.biorxiv.org/content/10.1101/2020.08.09.243048v1

Oculudentavis khaungraae was described based on a tiny skull trapped in amber. The slender tapering rostrum with retracted osseous nares, large eyes, and short vaulted braincase led to its identification as the smallest avian dinosaur on record, comparable to the smallest living hummingbirds. Despite its bird-like appearance, Oculudentavis showed several features inconsistent with its original phylogenetic placement. Here we describe a more complete, specimen that demonstrates Oculudentavis is actually a bizarre lizard of uncertain position. The new interpretation and phylogenetic placement highlights a rare case of convergent evolution rarely seen among reptiles. Our results re-affirm the importance of Myanmar amber in yielding unusual taxa from a forest ecosystem rarely represented in the fossil record.

 

[Fred Ruhe]

Alain DUBOIS, 2020

Nomenclatural consequences of the Oculudentavis khaungraae case, with comments on the practice of 'retraction' of scientific publications.

ZOOSYSTEMA 42(23): 475-482
doi: https://doi.org/10.5252/zoosystema2020v42a23.
http://sciencepress.mnhn.fr/en/periodiques/zoosystema/42/23

Free pdf:
http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2020v42a23.pdf

ABSTRACT

The recent publication in the journal Nature of a paper describing a new fossil as a ‘hummingbirdsized dinosaur’, followed immediately by a rebuttal stating that it was in fact a lizard, and then by the ‘retraction’ of the original paper, raised concerns about the nomenclatural availability of the new binomen Oculudentavis khaungraae that it introduced. It is shown here that so-called ‘retraction’, by authors, editors or publishers, of a controversial paper, has no bearing under the Rules of the Code on the nomenclatural availability of the paper and of the new nomina or nomenclatural acts it may contain, which can be withdrawn only by the International Commission on Zoological Nomenclature acting under its Plenary Power. It is furthermore argued that the principle of ‘retraction’ of scientific publications itself is anti-scientific, harmful to the history of science, and belongs in the domain of ‘denialism’: it should be fully abandoned by serious scientific journals.

Enjoy,

Fred

 

[albertonykus]

Li, Z.-H., W. Wang, H. Hu, M. Wang, H.Y. Yi, and J. Lu (2020)
Reanalysis of Oculudentavis shows it is a lizard
Vertebrata PalAsiatica (advance online publication)
doi: 10.19615/j.cnki.1000-3118.201020
http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/202010/t20201028_5723330.html

The recent finding of a fossil entombed in a Late Cretaceous amber – Oculudentavis khaungraae – was claimed to represent a humming bird-sized dinosaur. Regardless of the intriguing evolutionary hypotheses about the bauplan of Mesozoic dinosaurs (including birds) posited therein, this enigmatic animal demonstrates various morphologies resembling lizards. If Oculudentavis was a bird, it challenges several fundamental morphological differences between Lepidosauria and Archosauria. Here we reanalyze the original computed tomography scan data of the holotype of Oculudentavis khaungraae (HPG-15-3). Morphological evidences demonstrated here highly contradict the avian or even archosaurian phylogenetic placement of the species. In contrast, our analysis revealed multiple skull morphologies of HPG-15-3 resembling those of squamates, including pleurodont marginal teeth, an open infratemporal fenestra, and the presence of palatal dentition. Based on these new morphological information, the phylogenetic position of Oculudentavis was analyzed in a data matrix sampling across the Diapsida. Taxon sampling of the data matrix included multiple species of lizards, birds, and major clades in Lepidosauromorpha and Archosauromorpha. In the strict consensus tree, Oculudentavis is nested within Squamata. These results show that morphology of the Oculudentavis khaungraae holotype supports a squamate rather than avian or dinosaurian affinity of the species.