Calsoyasuchus Temporal range: Early Jurassic, | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauria |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Clade: | Crocodyliformes |
Family: | † Goniopholididae |
Genus: | † Calsoyasuchus Tykoski et al., 2002 |
Type species | |
†Calsoyasuchus valliceps Tykoski et al., 2002 |
Calsoyasuchus (meaning "[Dr. Kyril] Calsoyas' crocodile") is a genus of crocodylomorph [1] that lived in the Early Jurassic. Its fossilized remains were found in the Sinemurian-Pliensbachian-age Kayenta Formation on Navajo Nation land in Coconino County, Arizona, United States. Formally described as C. valliceps, it is known from a single incomplete skull which is unusually derived for such an early crocodile relative. This genus was described in 2002 by Ronald Tykoski and colleagues; the specific name means "valley head" and refers to a deep groove along the midline of the nasal bones and frontal bones. [2] It has often been interpreted as the earliest diverging member of Goniopholididae, but other studies have recovered it in various other positions.
The holotype skull (TMM 43631-1) that would be named Calsoyasuchus was discovered in 1997 by members of an expedition composed of crews from Texas Memorial Museum of the University of Texas at Austin, the Museum of Comparative Zoology at Harvard University, and the Seba Dalkai Navajo Nation School. It was found in the middle third of the silty facies of the Kayenta Formation, near the Adeii Eechii Cliffs. The skull is missing the lower jaws, part of the palate, most of the suspensorium (the bones that make up the region where the upper and lower jaws articulate), and the occiput and braincase. Sutures between the skull bones are mostly fused. As preserved, it is about 38.0 centimeters (15.0 in) long, making its owner a moderately sized animal. [2]
The skull was long, low, and curved so that both extremities were higher than the middle. The premaxilla bones that formed the end of the snout were enlarged to form a wide tip; there were at least four teeth in the right premaxilla and five in the left. The left maxilla (main tooth-bearing bone of the upper jaw) is more complete than the right, and had at least 29 teeth. There was a deep groove along the midline of the nasals and the frontals; the frontals were fused into a single bone, as is seen in other adult mesoeucrocodylians. Unlike derived neosuchians, it had external antorbital fenestrae. Tykoski and colleagues subjected the skull to CT scanning, which revealed internal cavities and air passages, and showed that it had a double-walled secondary palate similar to that of true crocodylians, and similar pneumatic cavities as well. [2]
Tykoski and colleagues performed a cladistic phylogenetic analysis with their new taxon, and found that it grouped with Goniopholis , Sunosuchus , and, most closely, with Eutretauranosuchus in a weakly supported clade, Goniopholididae. They noted that the skull of Calsoyasuchus is very similar to some goniopholid skulls from the younger, Upper Jurassic Morrison Formation. Calsoyasuchus pushes back the earliest occurrence of goniopholids from the Late Jurassic into the Early Jurassic, and not only helps to bridge a temporal gap between groups of crocodyliforms, but also a morphological gap. It also implies that some groups of crocodyliforms have long undiscovered histories. [2]
In 2011, Calsoyasuchus was recovered as the basalmost goniopholidid and the sister taxon to all other goniopholidids. [3]
Neosuchia |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Its placement as a goniopholid is not uncontested. A cladistic analysis of Crocodylomorpha published by Wilberg et al. (2019) in their discussion of crocodylomorph paleobiology recovers Calsoyasuchus as a close relative of the basal mesoeucrocodyliform Hsisosuchus . [4] A 2022 analysis found it to be the sister group of Thalattosuchia. [5]
During the Sinemurian and Pliensbachian ages of the Early Jurassic, the Kayenta Formation had a diverse fauna, with the remains of caecilians, frogs, turtles, at least five other taxa of crocodylomorphs, pterosaurs, theropod, sauropodomorph, and ornithischian dinosaurs, and early relatives of mammals (tritylodontids and morganucodontids). [2]
Goniopholis is an extinct genus of goniopholidid crocodyliform that lived in Europe and North America during the Late Jurassic and Early Cretaceous. Like other goniopholidids, it resembled living crocodilians, and probably had a similar ecology as semi-aquatic ambush predators.
Razanandrongobe is a genus of carnivorous ziphosuchian crocodyliform from the Middle Jurassic of Madagascar. It contains the type and only species Razanandrongobe sakalavae, named in 2004 by Simone Maganuco and colleagues based on isolated bones found in 2003. The remains, which included a fragment of maxilla and teeth, originated from the Bathonian-aged Sakaraha Formation of Mahajanga, Madagascar. While they clearly belonged to a member of the Archosauria, Maganuco and colleagues refrained from assigning the genus to a specific group because the fragmentary remains resembled lineages among both the theropod dinosaurs and crocodylomorphs.
Rugosuchus is an extinct genus of neosuchian crocodyliform from the late Early Cretaceous of China. It is known from most of a skull, a partial postcranial skeleton, and a second partial skeleton including part of the hips. It was described by Xiao-Chun Wu and colleagues in 2001, with R. nonganensis as the type species. At the time of its description, it was the most complete crocodyliform from northeastern China, and only the second known.
Goniopholididae is an extinct family of moderate-sized semi-aquatic neosuchian crocodyliformes. Their bodyplan and morphology are convergent on living crocodilians. They lived across Laurasia between the Middle Jurassic and the Late Cretaceous.
Eutretauranosuchus is an extinct genus of goniopholidid crocodyliform. E. delfsi is the only known species within the genus.
Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to Crocodylus niloticus than to Notosuchus terrestris. Members of Neosuchia generally share a crocodilian-like bodyform adapted to freshwater aquatic life, as opposed to the terrestrial habits of more basal crocodylomorph groups. The earliest neosuchian is suggested to be the Early Jurassic Calsoyasuchus, which lived during the Sinemurian and Pliensbachian stages in North America. It is often identified as a member of Goniopholididae, though this is disputed, and the taxon may lie outside Neosuchia, which places the earliest records of the group in the Middle Jurassic.
Amphicotylus is an extinct genus of goniopholidid mesoeucrocodylian from the Tithonian of Colorado, Wyoming, and Oklahoma. It was described in 1878.
Kayentasuchus is a genus of sphenosuchian, a type of basal crocodylomorph, the clade that comprises the crocodilians and their closest kin. It is known from a single skeleton found in rocks of the Sinemurian-Pliensbachian-age Lower Jurassic Kayenta Formation, northeastern Arizona.
Kayentachelys is an extinct genus of turtle known only from the "silty facies" of the Lower Jurassic Kayenta Formation in northeastern Arizona on the lands of the Navajo Nation.
Shartegosuchidae is an extinct family of Late Jurassic and Early Cretaceous crocodyliforms. The family is named after the Late Jurassic Shar Teeg Beds in southwestern Mongolia, from which most shartegosuchid remains have been found. Five genera are currently assigned to Shartegosuchidae: Shartegosuchus, Nominosuchus, Kyasuchus, Adzhosuchus, and Fruitachampsa. Shartegosuchus, Nominosuchus, and Adzhosuchus all come from Shar Teeg, while Kyasuchus is known from the Early Cretaceous of Russia. Fruitachampsa is known from the Late Jurassic Morrison Formation of the western United States.
Sunosuchus is an extinct genus of goniopholidid mesoeucrocodylian. Fossils are known from China, Kyrgyzstan, and Thailand and are Jurassic in age, although some may be Early Cretaceous. Four species are currently assigned to the genus: the type species S. miaoi and the species S. junggarensis, S. shartegensis, and S. shunanensis. All species are from China. Goniopholis phuwiangensis, also from Thailand, was reassigned to Sunosuchus by Andrade et al. (2011). The material from Kyrgyzstan has not been assigned to any species.
Shantungosuchus is an extinct genus of Early Cretaceous crocodyliform found in China. It includes three species: Shantungosuchus chuhsienensis and S. brachycephalus, which were both described by Yang Zhongjian – usually referred to as "Young" – in 1961 and 1982, and S. hangjinensis, which was described by Xiao-Chun Wu et al in 1994. S. chuhsienensis is the type for this genus.
Sarahsaurus is a genus of basal sauropodomorph dinosaur which lived during the Early Jurassic period in what is now northeastern Arizona, United States.
Anteophthalmosuchus is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England, eastern Spain, and western Belgium.
Hulkepholis is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England and eastern Spain. It contains two species, the type species, Hulkepholis willetti, and also H. plotos. Hulkepholis is most closely related to both species of Anteophthalmosuchus.
Chalawan is an extinct genus of pholidosaurid mesoeucrocodylian known from the Late Jurassic or Early Cretaceous Phu Kradung Formation of Nong Bua Lamphu Province, northeastern Thailand. It contains a single species, Chalawan thailandicus, with Chalawan shartegensis as a possible second species.
Coelophysis? kayentakatae is an extinct species of neotheropod dinosaur that lived approximately 200–196 million years ago during the early part of the Jurassic Period in what is now the southwestern United States. It was originally named Syntarsus kayentakatae, but the genus Syntarsus was found to be preoccupied by a Colydiine beetle, so it was moved to the genus Megapnosaurus, and then to Coelophysis. A recent reassessment suggests that this species may require a new genus name.
Coelognathosuchia is an extinct clade of neosuchian crocodyliforms that includes all taxa more closely related to the family Pholidosauridae than to Bernissartia fagesii or Eusuchia. Martin et al. (2014) named the clade after finding goniopholidids and pholidosaurids to group together in their phylogenetic analysis of crocodyliform evolutionary relationships. In their analysis, Pholidosauridae was monophyletic and Goniopholididae was paraphyletic, being an assemblage of successively more basal taxa within Coelognathosuchia. Coelognathosuchia itself was positioned near the base of the larger clade Neosuchia as the sister group to a clade containing the Early Cretaceous neosuchian Bernissartia and Eusuchia, the group that includes all modern crocodilians and their closest extinct relatives.
Turnersuchus is an extinct genus of thalattosuchian, a group of marine crocodylomorphs, from the Pliensbachian of the United Kingdom. It is the oldest diagnostic member of Thalattosuchia and was also found to be the group's most basal member, being situated outside the two major groups Metriorhynchoidea and Teleosauroidea. Subsequently, this genus is considered to be of great importance to understanding the relationship between thalattosuchians and other crocodylomorphs as well as their rapid diversification during the early Jurassic. Turnersuchus is a monotypic genus, meaning it includes only a single species, Turnersuchus hingleyae.
Ophiussasuchus is an extinct genus of goniopholid neosuchian from the Upper Jurassic Lourinhã Formation of Portugal. It was a medium-sized goniopholid, about 2.5 m to 3 m long, with a flattened skull and mesorostrine snout. Although most closely related to the Cretaceous goniopholids of Europe, such as Hulkepholis and Anteophthalmosuchus, Ophiussasuchus shares a variety of characteristics with more basal taxa from the Jurassic of Asia and North America. This could suggest that it either represents a transitional form or that this genus independently re-evolved these ancestral features. Ophiussasuchus is a monotypic genus, only including a single species: O. paimogonectes.