Eutretauranosuchus Temporal range: Late Jurassic ~ | |
---|---|
Jaws on display in the Cincinnati Museum Center | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauria |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Clade: | Crocodyliformes |
Family: | † Goniopholididae |
Genus: | † Eutretauranosuchus Mook, 1967 |
Type species | |
†Eutretauranosuchus delfsi Mook, 1967 |
Eutretauranosuchus is an extinct genus of goniopholidid crocodyliform. E. delfsi is the only known species within the genus.
The holotype of Eutretauranosuchus delfsi was discovered by Edwin Delfs in 1957 among remains recovered from the Morrison Formation in Canon City, Colorado. It was first described in detail by Charles Mook in 1967. [1] The fossil remains consisted of an almost-complete skull as well as some limb bones. [1]
The name Eutretauranosuchus was given by Delfs upon its discovery in reference to its "doubly pierced palate". The holotype specimen was named E. delfsi by Mook in tribute to Delfs. [2]
Mook found E. delfsi differs significantly from previously described Mesosuchian crocodiles. This specimen was deemed part of a new species because of its extremely elongated internal narial aperture, which was notably longer than those of previously described specimens of similar size. [1] Mook also described an additional, smaller opening located anterior to the internal nares, divided by the palatine processes, which was hypothesized to have entered the narial passage. [1] According to Mook, these features were an indication of a wide-ranged specialization among Goniopholididae and indicated the described specimen is a holotype for a new genus. [1]
Recent findings suggest that Mook's original description of an additional nasal opening was incorrect and that this opening was part of an elongated choana that is extremely constricted medially by the expansion of the palatines, giving the illusion of a separate anteriorly located opening due to its hourglass-shape—as is commonly described in other E. delfsi, Amphicotylus lucasii and A. gilmorei specimens. [3]
Characteristics of E. delfi skulls include an elongated and platyrostral skull, posterolateral depressions on the alveolar maxillary process, minimal lateral undulation of the tooth row (maxillary), broadened nasals located anteriorly to the prefrontals, a lack of contact between the nasals and external nares, a flattened and broad innerfenestral bar with rims that are raised along the supratemporal fenestra, and a nasopharyngeal septum formed by the anterior divergence of the vomeral processes. [4] The lacrimal bone is rectangular and in dorsal view has an anteroposterior length that is two times its width. [4] The lacrimal is contacted by the prefrontal laterally along its length, which separates the prefrontal from the nasal. [4] A large postorbital bar with a triangular cross-section creates a separation between the orbit and the infratemporal fenestra. [4] The quadratojugal has two regions: a smaller dorsal part that lacks dermal pitting, and a larger ventral region that is pitted and forms the bottom half of the infratemporal process, creating a significant indentation that is considered characteristic of this genus. [4]
While the majority of Goniopholididae have historically been categorized by flattened snouts and posterolaterally located maxillary depressions, there remains great variation within their palatal anatomy. [4] Most Morrison Formation goniopholidids display an ‘incomplete’ secondary palate, in which there is no ventral floor in the nasopharyngeal passage. Differences among palatal anatomy have been observed between Goniopholididae taxa found from the Cretaceous in Europe and species found in North America. [4] European specimens such as G. simus and G.siplingi have a secondary bony palate formed from the palatines and maxillary processes. North American goniopholidids have maxillae and palatines that do not contact, resulting in a more open palate and a ventrally exposed bony nasopharyngeal passage. [4]
The postcranial skeleton of Goniopholididae is characterized by amphicoelous vertebrae, two rows of paravertebral osteoderms with "peg and groove" articulation and polygonal ventrally located osteoderms. [5] Goniopholididae commonly have a closed paravertebral armor bracing system. The anteroposteriorly located crest on the ventral surfaces of Goniopholididae dorsal osteoderms has been hypothesized to be evidence that the epaxial musculature attached medially to a single paravertebral osteoderm, which is different from the three groups of epaxial musculature that attach to separate osteoderms in extant crocodylians.
Eutretauranosuchus is currently known from specimens found in the Upper Jurassic Dry Mesa Dinosaur Quarry in Canon City, Colorado; the Brushy Basin Member in Western Colorado; and the Bone Cabin Quarry site in Wyoming—all of which are parts of the Morrison Formation. [4] Other Gonopholididae appear in strata from the Early Jurassic to Late Cretaceous. The family is classed as a Laurasian group, with specimens located in North America, Europe, and South-East Asia. Specimens from this group are often found in estuarine and freshwater deposits. [6]
Goniopholidid crocodilians, including Eutretauranosuchus, are widely categorized as semi-aquatic forms. [7] Preserved specimens indicate Eutretauranosuchus are moderately sized with an average estimated weight of 50–60 kg. [7] The size and length of Goniopholididae specimens found in the Morrison Formation, as well as striated teeth, [1] support the hypothesis that Eutretauranosuchus were carnivorous, feeding on prey such as insects, fish, small reptiles, mammals and dinosaurs. [7]
E. delfsi is the only recognized species of Eutretauranosuchus. Other genera of Goniopholididae include Amphicotylus , Goniopholis , Sunosuchus , and Calsoyasuchus . [2]
The exact phylogenetic placement of Eutretauranosuchus remains ambiguous. Phylogenetic analysis by Smith et al. in 2010 [2] provides evidence that Eutretauranosuchus, Calsoyasuchus and Sunosuchus are closely related, and these findings are widely supported. However, while many publications support the phylogenetic placement of Eutretauranosuchus within the family of Goniopholididae, there is debate over whether it is more closely related to Goniopholis or Sunosuchus. Alternatively, phylogenetic assessment by J.R. Foster in 2006 considers Eutretauranosuchus to be most closely related to Pholidosaurus and dyrosauridae, and belonging to a larger clade that includes Bernissartia, Eusuchians and Goniopholis. [8] Further research is needed to clarify these disputes.
Phylogenetic analysis by Allen (2012) [3] claims that North American goniopholidid forms are monophyletic, excluding all other goniopholidids. It is proposed that this North America specific clade can be defined by channel-like, extremely elongated choanae that completely separate the palatines and that within this clade exists a further distinguished clade of the forms found in the Morrison Formation, which are defined by triangular prefrontals that rostrally extend past the lacrimals, preventing lacrimal contact with the nasals.
A recent study re-evaluated evolutionary history in relation to the Triassic-Jurassic mass extinction event. It concluded that the basal phylogenetic positioning of the goniopholidid crocodylomorph Calsoyasuchus valliceps suggests a substantial number of ghost lineages that should exist at the base of the crocodylomorphs. [9] Furthermore, they reported an increase in crocodylomorph disparity across the Triassic-Jurassic boundary, which suggests there was rapid radiation of adaptation among crocodylomorphs. They hypothesize this was a result of the extinction's "decimation" of pseudosuchian and tetrapod lineages. The study concludes that the extinction was important for the evolutionary success of Goniopholididae.
A phylogenetic analysis by Brandelise de Andrade et al. [10] is shown in the following cladogram:
Neosuchia |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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.
Haplocanthosaurus is a genus of intermediate sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period, 155 to 152 million years ago. The type species is H. priscus, and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado, United States. Haplocanthosaurus specimens have been found in the very lowest layer of the Morrison Formation, along with Hesperosaurus mjosi, Brontosaurus yahnahpin, and Allosaurus jimmadseni.
Nodocephalosaurus is a monospecific genus of ankylosaurid dinosaur from New Mexico that lived during the Late Cretaceous in what is now the De-na-zin member of the Kirtland Formation. The type and only species, Nodocephalosaurus kirtlandensis, is known only from a partial skull. It was named in 1999 by Robert M. Sullivan. Nodocephalosaurus has an estimated length of 4.5 metres and weight of 1.5 tonnes. It is closely related and shares similar cranial anatomy to Akainacephalus.
Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was a fairly large predator, measuring up to 4 metres (13 ft) long.
Anatosuchus is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described by a team of palaeontologists led by the American Paul Sereno in 2003, in the Journal of Vertebrate Paleontology. Its duck-like snout coincidentally makes it resemble a crocoduck, an imagined hybrid animal with the head of a crocodile and the body of a duck.
Calsoyasuchus is a genus of crocodylomorph 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. It has often been interpreted as the earliest diverging member of Goniopholididae, but other studies have recovered it in various other positions.
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.
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.
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.
Arenysuchus is an extinct monospecific genus of allodaposuchid eusuchian crocodylomorph from Late Cretaceous deposits of north Spain. It is known from the holotype MPZ ELI-1, a partial skull from Elías site, and from the referred material MPZ2010/948, MPZ2010/949, MPZ2010/950 and MPZ2010/951, four teeth from Blasi 2 site. It was found by the researchers José Manuel Gasca and Ainara Badiola from the Tremp Formation, in Arén of Huesca, Spain. It was first named by Eduardo Puértolas, José I. Canudo and Penélope Cruzado-Caballero in 2011 and the type species is Arenysuchus gascabadiolorum.
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.
Europelta is a monospecific genus of nodosaurid dinosaur from Spain that lived during the Early Cretaceous in what is now the lower Escucha Formation of the Teruel Province. The type and only species, Europelta carbonensis, is known from two associated partial skeletons, and represents the most complete ankylosaur known from Europe. Europelta was named in 2013 by James I. Kirkland and colleagues. Europelta has an estimated length of 5 metres and weight of 1.3 tonnes, making it the largest member of the clade Struthiosaurini.
Anthracosuchus is an extinct genus of dyrosaurid crocodyliform from the Paleocene of Colombia. Remains of Anthracosuchus balrogus, the only known species, come from the Cerrejón Formation in the Cerrejón mine, and include four fossil specimens with partial skulls. Anthracosuchus differs from other dyrosaurids in having an extremely short (brevirostrine) snout, widely spaced eye sockets with bony protuberances around them, and osteoderms that are smooth and thick. It is one of the most basal dyrosaurids along with Chenanisuchus and Cerrejonisuchus.
Chinatichampsus is an extinct genus of crocodilian from the Devil's Graveyard Formation of Texas, specifically the Dalquest Desert Research Site. It is a monotypic genus, containing only the type species Chintanichampsus wilsonorum. A single specimen, TMM 45911–1, was first discovered in 2010. Chinatichampsus is the most basal Eocene caimanine, dating to between 42.8 and 41.5 million years ago, and is considered to be more basal than Protocaiman.
Varanosuchus is an extinct genus of atoposaurid neosuchian from the Early Cretaceous Sao Khua Formation of Thailand. Varanosuchus is known from three individuals which preserve assorted postcranial material and a complete skull. The skull of Varanosuchus was altirostral, meaning it wasn't flattened like in modern crocodilians and instead much deeper, while the limbs were slender and straight, leading to it somewhat resembling a monitor lizard. Little is known about the ecology of atoposaurids, however, based on the slender, erect limbs, the altirostral skull and the well ornamented osteoderms it has been suggested that Varanosuchus was a terrestrial animal with some semi-aquatic affinities. Only a single species is recognized, Varanosuchus sakonnakhonensis.
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.