Cteniogenys

{{Speciesbox

| fossil_range = Middle-Late Jurassic, {{fossilrange|167.7|150}}

| image = Cteniogenys_dentary.jpg

| image_caption = Dentary of the holotype specimen VP.001088

| parent_authority = Gilmore, 1928

| grandparent_authority = Seiffert, 1975

| genus = Cteniogenys

| species = antiquus

| authority = Gilmore, 1928

}}

Cteniogenys is a genus of choristodere, a morphologically diverse group of aquatic reptiles. It is part of the monotypic family Cteniogenidae.J. Seiffert. 1975. Upper Jurassic lizards from central Portugal. Contribuição para o conhecimento da Fauna do Kimerridgiano da Mina de Lignito Guimarota (Leiria, Portugal). Serviços Geológicos de Portugal, Memória (Nova Série) 22:7-85 The type and only named species, C. antiquus, was named in 1928 by Charles W. Gilmore.C. W. Gilmore. 1928. Fossil lizards of North America. Memoirs of the National Academy of Sciences. 22(3):1-201 The holotype, VP.001088, was collected in the Morrison Formation (Como Bluff), Wyoming in 1881 by William H. Reed. More specimens have been discovered since then, including specimens from the Late Jurassic of Portugal and Middle Jurassic of Britain, which have not been assigned to species.

Description

Cteniogenys was {{convert|25|to|50|cm|in}} long, and probably weighed less than {{convert|500|g|lb}}. The skull of this genus was long and slender, and the jaws had numerous conical teeth. Cteniogenys in the Morrison probably fed on insects and small fish. It is mostly known from freshwater sites (rivers and ponds), and is a rare find in the formation (only 60 specimens out of over 2,800 total vertebrate specimens known from the formation), mostly known from northern outcrops (particularly Wyoming); this may reflect a preservation bias against small animals in terrestrial settings, rather than an accurate reflection of Cteniogenys populations in the Morrison.

Distribution

Fossils of Cteniogenys are known from the upper Middle Jurassic (Bathonian) aged Forest Marble Formation and Kilmaluag Formation of Britain, the Late Jurassic (Kimmeridgian) aged Alcobaça Formation of Portugal, and the Late Jurassic-age Morrison Formation of western North America, indeterminate similar remains are also known from the Callovian aged Balabansai Formation of Kyrgyzstan and{{Cite journal|last1=Matsumoto|first1=R.|last2=Evans|first2=S. E.|date=2010|title=Choristoderes and the freshwater assemblages of Laurasia|url=http://revistas.ucm.es/index.php/JIGE/article/view/JIGE1010220253A|journal=Journal of Iberian Geology|volume=36|issue=2|pages=253–274|doi=10.5209/rev_JIGE.2010.v36.n2.11|issn=1698-6180|doi-access=free}} the Bathonian aged Itat Formation of western Siberia,{{Cite journal|date=2016|title=Middle Jurassic vertebrate assemblage of Berezovsk coal mine in western Siberia (Russia)|journal=Global Geology|volume=19|issue=4|pages=187–204|doi=10.3969/j.issn.1673-9736.2016.04.01}} and the Berriasian aged Angeac-Charente bonebed in France.Ronan Allain, Romain Vullo, Lee Rozada, Jérémy Anquetin, Renaud Bourgeais, et al.. [https://hal.archives-ouvertes.fr/hal-03264773/document Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J/K boundary]. Geodiversitas, Museum National d’Histoire Naturelle Paris, In press. ffhal-03264773f

A handful of skull and jaw fragments from the Late Cretaceous Oldman Formation and Dinosaur Park Formation in Canada were assigned to Cteniogenys by Gao and Fox (1998).Gao, K, and Fox, R.C., 1998. New choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Paleocene, Alberta and Saskatchewan, Canada, and phylogenetic relationships of the Choristodera. Zool J Linn Soc. 124:303–353. Given the long gap in time, however, Gao et al. (2005) cautioned that these remains could constitute a different, as-yet undetermined genus. In their description of new material of Khurendukhosaurus, Matsumoto et al. (2009) agreed that the putative Cretaceous occurrence of Cteniogenys did not belong to that genus and represents an indeterminate choristoderan, possibly a new genus.{{cite book |last=Gao |first=Keqin |author2=Brinkman, Donald E. |editor=Currie, Phillip J. |editor2=Koppelhus, Eva |title=Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed |chapter=Choristoderes from the Park and its vicinity |year=2005 |publisher=Indiana University Press |location=Bloomington |pages=[https://archive.org/details/dinosaurprovinci0000unse/page/221 221–234] |isbn=0-253-34595-2 |chapter-url=https://archive.org/details/dinosaurprovinci0000unse/page/221 }}Matsumoto, R, Suzuki, S, Tsogtbaatar, K, Evans, SE, 2009. New material of the enigmatic reptile Khurendukhosaurus (Diapsida: Choristodera) from Mongolia. Naturwissenschaften 96:233–242.

Systematics

The genus was named in 1928 by Charles W. Gilmore on the basis of a lower jaw collected during the late 19th century by Othniel Charles Marsh's workers at Como Bluff. He tentatively described the genus as a lizard, noting that it could instead be a frog.{{cite book |last=Foster | first=John |title=Jurassic West: The Dinosaurs of the Morrison Formation and Their World |pages=146–148 |publisher=Indiana University Press |location=Bloomington, Indiana |isbn=978-0-253-34870-8 |year=2007 |oclc=77830875}} New material of Cteniogenys from Europe prompted Susan E. Evans to reclassify it as an early choristodere in 1989.{{cite journal |last=Evans |first=Susan E. |year=1989 |title=New material of Cteniogenys (Reptilia: Diapsida) and a reassessment of the phylogenetic position of the genus |journal=Neues Jahrbuch für Geologie und Paläontologie, Monatshefte |volume=1989 |issue=10 |pages=577–589|doi=10.1127/njgpm/1989/1989/577 }} To date it is only known from fragmentary specimens. In phylogenic analyses it has been found to the basal most choristodere.{{Cite journal|last1=Matsumoto|first1=Ryoko|last2=Dong|first2=Liping|last3=Wang|first3=Yuan|last4=Evans|first4=Susan E.|date=2019-06-18|title=The first record of a nearly complete choristodere (Reptilia: Diapsida) from the Upper Jurassic of Hebei Province, People's Republic of China|url=https://www.tandfonline.com/doi/full/10.1080/14772019.2018.1494220|journal=Journal of Systematic Palaeontology|language=en|volume=17|issue=12|pages=1031–1048|doi=10.1080/14772019.2018.1494220|s2cid=92421503|issn=1477-2019}}

{{clade

|label1=Choristodera

|1={{clade

|1=Cteniogenys

|2={{clade

|label1=Neochoristodera

|1={{clade

|1=Ikechosaurus pijiagouensis

|2=Ikechosaurus sunailinae

|3=Tchoiria namsari

|4=Tchoiria klauseni

|label5=Champsosaurus