Coeruleodraco

Last updated

Coeruleodraco
Temporal range: Oxfordian, 163.5–157.3  Ma
Coeruleodraco paratype.jpg
Paratype specimen
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Choristodera
Genus: Coeruleodraco
Matsumoto et al., 2019
Type species
Coeruleodraco jurassicus
Matsumoto et al., 2019

Coeruleodraco is an extinct genus of choristoderan known from the Late Jurassic (Oxfordian) Tiaojishan Formation in China. Coeruleodraco is significant as the most complete Jurassic choristodere taxon, as the only other named Jurassic choristodere Cteniogenys is based on fragmentary remains. Although similar to Philydrosaurus in its proportions and postcranial characters, it is distinct in retaining several apparently plesiomorphic characters, including a short snout, paired external nares and an open lower temporal fenestra. [1]

Contents

Description

CT scan of the skull of the holotype Coeruleodraco.jpg
CT scan of the skull of the holotype

The skeleton was small, about 20.3 cm (8.0 inches) in length, not including the tail. The tail is incomplete, but including its estimated length, the total length of the skeleton would have been closer to 40.0 cm (15.7 inches). Coeruleodraco had a generalized, lizard-like body type. This is similar to some early choristoderes (like Cteniogenys , Philydrosaurus , and Monjurosuchus ), but contrasts with other choristodere body types including long-necked forms such as Hyphalosaurus , and gharial-like forms such as Champsosaurus and other neochoristoderes. [1]

Life reconstruction of C. jurassicus compared to a human hand Coeruleodraco NT.jpg
Life reconstruction of C. jurassicus compared to a human hand

The skull had a short, pointed snout with about 38 teeth on each side (a low number by choristodere standards). It also had two nares (nostril holes). While paired nares are standard in most reptile groups, almost all other choristoderes (except Lazarussuchus) typically have one single hole in the skull for the nostrils, making Coeruleodraco's retention of paired nares a plesiomorphic ("primitive") feature relative to most other choristoderes. In common with other choristoderes, Coeruleodraco has elongated prefrontal bones which meet each other at the top of the snout, separating a pair of small, triangular nasal bones in the process. The nasals are so reduced in size (especially compared to Philydrosaurus) that they are completely surrounded by the prefrontals and premaxillary bones, and fail to contact the toothed maxillary bones. The postorbital and postfrontal bones (which lie behind the eye) are separate from each other; in many other choristoderes these bones fuse into a single postorbitofrontal bone. The rear of the skull is not particularly unusual, with each side of the skull having two holes known as temporal fenestrae (as with other diapsids). The upper temporal fenestra is not elongated (unlike neochoristoderes), but the lower temporal fenestra is low and long. The rear edge of each upper temporal fenestra was formed by the squamosal bone, which was ornamented with small spines. [1]

The postcranial skeleton was very similar to that of Philydrosaurus. The neck was short, and its vertebrae had low, swollen neural arches (upper portions). There were six or seven vertebrae in the neck, 16 in the torso, three in the hip, and more than 24 in the tail, which is incomplete. Vertebrae were longer than high, and the neural arches were completely fused to the centra (lower, spool-shaped portions), in contrast to the condition in neochoristoderes. Vertebrae at the base of the tail were fused to fan-shaped ribs which projected straight out. Further down the tail, these ribs became shorter and rectangular. The humerus was robust, with a roughly-textured knob above the large entepicondyle. The plate-like ischium bone (which formed the rear lower part of the hip) had a distinct triangular prong along its rear edge. [1]

Classification

A group of phylogenetic analyses recovered Coeruleodraco as one of the earliest diverging members of a group of small-bodied Eurasian choristoderes. This group was likely a clade according to the parsimony analysis, in which case it was the sister taxon of the gharial-like neochoristoderes, although its monophyly is more uncertain under the bootstrap analysis. The only known genus of choristodere which diverged earlier than Coeruleodraco was Cteniogenys , which acquired a few specialized features independently of other choristoders. [1]

 Choristodera 

Cteniogenys sp.

Neochoristodera

Ikechosaurus pijiagouensis

Ikechosaurus sunailinae

Tchoiria namsari

Tchoiria klauseni

Champsosaurus

C. gigas

C. albertensis

Simoedosaurus

S. lemoinei

S. dakotensis

Coeruleodraco jurassicus

Monjurosuchus splendens (specimen BMNHC 073)

Monjurosuchus splendens (specimen DR0003C)

Philydrosaurus

P. proseilus (specimen PKUP V2001)

P. proseilus (specimen LPMC021)

Lazarussuchus

L. inexpectatus

Lazarussuchus sp.

L. dvoraki

Khurendukhosaurus orlovi

Hyphalosaurus sp. (specimen IVPP 14560)

Hyphalosaurus lingyuanensis (specimen IVPP 11075)

Shokawa ikoi

In the analyses of Dong and colleagues (2020) it was recovered in a more basal position, outside the clade containing Neochoristodera + the newly named "Allochoristoderes", and in a polytomy with the newly named Heishanosaurus : [2]


Choristodera

Cteniogenys sp.

Heishanosaurus pygmaeus

Coeruleodraco jurassicus

Neochoristodera

Ikechosaurus pijiagouensis

Ikechosaurus sunailinae

Tchoiria namsari

Tchoiria klauseni

Champsosaurus

C. gigas

C. albertensis

Simoedosaurus

S. lemoinei

S. dakotensis

"Allochoristodera"

Monjurosuchus splendens

Philydrosaurus

P. proseilus

P. proseilus

Lazarussuchus

L. inexpectatus

Lazarussuchus sp.

L. dvoraki

Khurendukhosaurus orlovi

Hyphalosaurus sp.

Hyphalosaurus lingyuanensis

Shokawa ikoi

Related Research Articles

<span class="mw-page-title-main">Archosauromorpha</span> Infraclass of reptiles

Archosauromorpha is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs rather than lepidosaurs. Archosauromorphs first appeared during the late Middle Permian or Late Permian, though they became much more common and diverse during the Triassic period.

<i>Champsosaurus</i> Extinct genus of reptiles

Champsosaurus is an extinct genus of crocodile-like choristodere reptile, known from the Late Cretaceous and early Paleogene periods of North America and Europe (Campanian-Paleocene). The name Champsosaurus is thought to come from champsai, (χαμψαι) said in an Ancient Greek source to be an Egyptian word for "crocodiles", and sauros, (σαύρος) Greek for "lizard". The morphology of Champsosaurus resembles that of gharials, with a long, elongated snout. It was native to freshwater environments where it likely preyed on fish, similar to living gharials.

<span class="mw-page-title-main">Choristodera</span> Extinct order of reptiles

Choristodera is an extinct order of semiaquatic diapsid reptiles that ranged from the Middle Jurassic, or possibly Triassic, to the late Miocene. Choristoderes are morphologically diverse, with the best known members being the crocodile-like neochoristoderes such as Champsosaurus. Other choristoderans had lizard-like or long necked morphologies. Choristoderes appear to have been confined to the Northern Hemisphere, having been found in North America, Asia, and Europe, and possibly also North Africa. Choristoderes are generally thought to be derived neodiapsids that are close relatives or members of Sauria.

<i>Monolophosaurus</i> Extinct genus of dinosaurs

Monolophosaurus is an extinct genus of tetanuran theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China. It was named for the single crest on top of its skull. Monolophosaurus was a mid-sized theropod at about 5 metres (16 ft) long or more.

<i>Pinacosaurus</i> Genus of ankylosaurid dinosaur from Late Cretaceous

Pinacosaurus is a genus of ankylosaurid thyreophoran dinosaur that lived in Asia during the Late Cretaceous, mainly in Mongolia and China.

<i>Askeptosaurus</i> Extinct genus of reptiles

Askeptosaurus is an extinct genus of askeptosauroid, a marine reptile from the extinct order Thalattosauria. Askeptosaurus is known from several well-preserved fossils found in Middle Triassic marine strata in what is now Italy and Switzerland.

<i>Shokawa</i> Extinct genus of reptiles

Shokawa is an extinct genus of choristoderan diapsid reptile, known from the Lower Cretaceous of Japan. It is only known from one species, Shokawa ikoi. The only known remains are a postcranial specimen lacking the skull, discovered at the KO2 locality in sediments belonging to the Okurodani Formation near the village of Shokawa in Gifu Prefecture. Shokawa possessed a long neck with at least 16 cervical vertebrae, and closely resembles and is closely related to the smaller choristoderan, Hyphalosaurus. The generic name refers to the village near where it was found, while the specific name honors the collector of the first specimen, one Mr. Ikoi Shibata.

<span class="mw-page-title-main">Thalattosauria</span> Extinct order of sea reptiles

Thalattosauria is an extinct order of prehistoric marine reptiles that lived in the middle to late Triassic period. Thalattosaurs were diverse in size and shape, and are divided into two superfamilies: Askeptosauroidea and Thalattosauroidea. Askeptosauroids were endemic to the Tethys Ocean, their fossils have been found in Europe and China, and they were likely semiaquatic fish eaters with straight snouts and decent terrestrial abilities. Thalattosauroids were more specialized for aquatic life and most had unusual downturned snouts and crushing dentition. Thalattosauroids lived along the coasts of both Panthalassa and the Tethys Ocean, and were most diverse in China and western North America. The largest species of thalattosaurs grew to over 4 meters (13 feet) in length, including a long, flattened tail utilized in underwater propulsion. Although thalattosaurs bore a superficial resemblance to lizards, their exact relationships are unresolved. They are widely accepted as diapsids, but experts have variously placed them on the reptile family tree among Lepidosauromorpha, Archosauromorpha, ichthyosaurs, and/or other marine reptiles.

<i>Lazarussuchus</i> Extinct genus of reptiles

Lazarussuchus is an extinct genus of amphibious reptile, known from the Cenozoic of Europe. It is the youngest known member of Choristodera, an extinct order of aquatic reptiles that first appeared in the Middle Jurassic. Fossils have been found in Late Paleocene, Late Oligocene, Early Miocene and Late Miocene deposits in France, Germany, and the Czech Republic. Two species have been named: the type species L. inexpectatus ("unexpected") from the late Oligocene of France. and L. dvoraki from the early Miocene of the Czech Republic. It was not a large animal; the skull of L. inexpectatus was only about 4.53 centimeters long (1.78 in), with the total preserved body and tail length being just over 30 centimetres. A complete specimen of Lazarussuchus with preserved soft tissue was found from the Late Paleocene of France, but has not been assigned to a species.

<i>Acerosodontosaurus</i> Extinct genus of reptiles

Acerosodontosaurus is an extinct genus of neodiapsid reptiles that lived during the Upper Permian of Madagascar. The only species of Acerosodontosaurus, A. piveteaui, is known from a natural mold of a single partial skeleton including a crushed skull and part of the body and limbs. The fossil was discovered in marine deposits of the Lower Sakamena Formation. In conjunction with several skeletal characteristics, this may indicate that Acerosodontosaurus individuals were at least partially aquatic.

<i>Vancleavea</i> Extinct genus of reptiles

Vancleavea is a genus of extinct, armoured, non-archosaurian archosauriforms from the Late Triassic of western North America. The type and only known species is V. campi, named by Robert Long & Phillip A Murry in 1995. At that time, the genus was only known from fragmentary bones including osteoderms and vertebrae. However, since then many more fossils have been found, including a pair of nearly complete skeletons discovered in 2002. These finds have shown that members of the genus were bizarre semiaquatic reptiles. Vancleavea individuals had short snouts with large, fang-like teeth, and long bodies with small limbs. They were completely covered with bony plates known as osteoderms, which came in several different varieties distributed around the body. Phylogenetic analyses by professional paleontologists have shown that Vancleavea was an archosauriform, part of the lineage of reptiles that would lead to archosaurs such as dinosaurs and crocodilians. Vancleavea lacks certain traits which are present in most other archosauriforms, most notably the antorbital, mandibular and supratemporal fenestrae, which are weight-saving holes in the skulls of other taxa. However, other features clearly support its archosauriform identity, including a lack of intercentra, the presence of osteoderms, an ossified laterosphenoid, and several adaptations of the femur and ankle bones. In 2016, a new genus of archosauriform, Litorosuchus, was described. This genus resembled both Vancleavea and more typical archosauriforms in different respects, allowing Litorosuchus to act as a transitional fossil linking Vancleavea to less aberrant archosauriforms.

<i>Monjurosuchus</i> Extinct genus of reptiles

Monjurosuchus is a genus of choristoderan reptile that lived in what is now China and Japan during the Early Cretaceous. It has large eyes, a rounded skull, robust legs with short claws, and a long, thin tail. Fossils have been found that preserve soft tissue, showing that it had soft skin and webbed feet.

<i>Khurendukhosaurus</i> Extinct genus of reptiles

Khurendukhosaurus is a genus of choristodere, a type of amphibious reptile. It is known from Lower Cretaceous rocks of Mongolia and Russia. Two species have been named. The type species, K. orlovi, was named in 1984 by Sigogneau–Russell and Efimov for the fragmentary postcranial skeleton PIN 3386/3. This specimen was discovered in the Albian-age Lower Cretaceous Khuren Dukh Formation Formation at Hüren Dukh, central Mongolia. The lake deposits at this site also contain fossils of the choristoderes Irenosaurus and Tchoiria. Other postcranial bones of K. orlovi have been found at this site as well.

<i>Philydrosaurus</i> Extinct genus of reptiles

Philydrosaurus is an extinct genus of choristoderan which existed in China during the Early Cretaceous. The type species P. proseilus was named in 2005. Philydrosaurus was found from the Jiufotang Formation and is slightly younger than Monjurosuchus, which was found from the Yixian Formation.

<i>Teraterpeton</i> Extinct genus of reptiles

Teraterpeton is an extinct genus of trilophosaurid archosauromorphs. It is known from a partial skeleton from the Late Triassic Wolfville Formation of Nova Scotia, described in 2003. It has many unique features seen in no other related form, including an elongated, toothless snout and large openings for the nostrils. Because of this, Teraterpeton was originally placed in its own family, Teraterpetidae, related to Trilophosaurus. Newer studies generally place it within Trilophosauridae.

Hauffiopteryx is an extinct genus of ichthyosaur known from Germany, Luxembourg and Somerset of the United Kingdom. Two species are known: H. typicus and H. altera.

<i>Jesairosaurus</i> Extinct genus of reptiles

Jesairosaurus is an extinct genus of early archosauromorph reptile known from the Illizi Province of Algeria. It is known from a single species, Jesairosaurus lehmani. Although a potential relative of the long-necked tanystropheids, this lightly-built reptile could instead be characterized by its relatively short neck as well as various skull features.

This glossary explains technical terms commonly employed in the description of dinosaur body fossils. Besides dinosaur-specific terms, it covers terms with wider usage, when these are of central importance in the study of dinosaurs or when their discussion in the context of dinosaurs is beneficial. The glossary does not cover ichnological and bone histological terms, nor does it cover measurements.

<i>Vadasaurus</i> Extinct genus of reptiles

Vadasaurus is an extinct genus of rhynchocephalian closely related to the aquatic pleurosaurids. Although this genus was not as specialized as the eel-like pleurosaurs for aquatic life, various skeletal features support the idea that it had a semiaquatic lifestyle. The type species, Vadasaurus herzogi, was described and named in 2017. It was discovered in the Solnhofen Limestone in Germany, which is dated to the Late Jurassic. The generic name "Vadasaurus" is derived from "vadare", which is Latin for "to go" or "to walk forth", and "saurus", which means "lizard". "Vadare" is the root of the English word "wade", which is the reason it was chosen for this genus, in reference to its perceived semiaquatic habits. The specific name, "herzogi", refers to Werner Herzog, a Bavarian filmmaker.

Heishanosaurus is an extinct genus of choristodere reptile from the Early Cretaceous of China. The type and currently only known species is Heishanosaurus pygmaeus. It is unusual as it is much more primitive than other known choristoderes from the Early Cretaceous of Asia, and retains many plesiomorphic characters.

References

  1. 1 2 3 4 5 Matsumoto, Ryoko; Dong, Liping; Wang, Yuan; Evans, Susan E. (2019). "The first record of a nearly complete choristodere (Reptilia: Diapsida) from the Upper Jurassic of Hebei Province, People's Republic of China" (PDF). Journal of Systematic Palaeontology. 17 (12): 1031–1048. doi:10.1080/14772019.2018.1494220. S2CID   92421503.
  2. Dong, Liping; Matsumoto, Ryoko; Kusuhashi, Nao; Wang, Yuanqing; Wang, Yuan; Evans, Susan E. (2020-08-02). "A new choristodere (Reptilia: Choristodera) from an Aptian–Albian coal deposit in China". Journal of Systematic Palaeontology. 18 (15): 1223–1242. doi:10.1080/14772019.2020.1749147. ISSN   1477-2019. S2CID   219047160.