Acynodon Temporal range: Santonian - Maastrichtian, | |
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Skull of Acynodon iberoccitanus (ACAP-FXl) | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauria |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Clade: | Crocodyliformes |
Clade: | Metasuchia |
Clade: | Neosuchia |
Clade: | Eusuchia |
Genus: | † Acynodon Buscalioni et al., 1997 |
Species | |
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Acynodon is an extinct genus of eusuchian crocodylomorph from the Late Cretaceous, with fossils found throughout Southern Europe.
The genus Acynodon contains three species: A. iberoccitanus, A. adriaticus, and A. lopezi. Fossils have been found in France, Spain, Italy, and Romania, dating back to the Santonian and Maastrichtian periods of the Late Cretaceous. [1]
When first described in 1997, it was placed within the family Alligatoridae. [2] New findings a decade later led to it being reclassified as a basal globidontan. [3] [1] Recent studies have since resolved Acynodon as a basal eusuchian crocodylomorph, outside of the Crocodylia crown group, and a close relative to Hylaeochampsa . [4] [5] [6]
The skull of Acynodon is extremely brevirostrine; it had a very short and broad snout compared to other known alligatorids. [3] Its dentition was quite derived, with enlarged molariform teeth and a lack of maxillary and dentary caniniform teeth, presumably an adaptation to feed on slow prey with hard shells. [1] The paravertebral osteoderms of Acynodon were distinctively double-keeled.
A. adriaticus was highly specialized to durophagy, likely in shallow, densely vegetated waters. It had an acute lateral snout profile of A. adriaticus in comparison to the more rounded shape of A. iberoccitanus. [7]
Allodaposuchus is an extinct genus of crocodyliforms that lived in what is now southern Europe during the Campanian and Maastrichtian stages, and possibly the Santonian stage, of the Late Cretaceous. Although generally classified as a non-crocodylian eusuchian crocodylomorph, it is sometimes placed as one of the earliest true crocodylians. Allodaposuchus is one of the most common Late Cretaceous crocodylomorphs from Europe, with fossils known from Romania, Spain, and France.
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ecologically diverse than modern crocodillians. The earliest and most primitive crocodylomorphs are represented by "sphenosuchians", a paraphyletic assemblage containing small-bodied, slender forms with elongated limbs that walked upright, which represents the ancestral morphology of Crocodylomorpha. These forms persisted until the end of the Jurassic. During the Jurassic, crocodylomorphs morphologically diversified into numerous niches, with the subgroups Neosuchia and the extinct Thalattosuchia adapting to aquatic life, while some terrestrial groups adopted herbivorous and omnivorous lifestyles. Terrestrial crocodylomorphs would continue to co-exist alongside aquatic forms until becoming extinct during the Miocene.
Boverisuchus is an extinct genus of planocraniid crocodyliforms known from the early to middle Eocene of Germany and western North America. It was a relatively small crocodyliform with an estimated total length of approximately 2.2–3.6 metres (7.2–11.8 ft).
Pachycheilosuchus is an extinct genus of neosuchian from the Early Cretaceous of Texas, United States. Previously known, in part, as the "Glen Rose form", this crocodylomorph is notable for its procoelous vertebrae, otherwise found only in derived eusuchian crocodilians, a thick margin on the maxillae, and a shield of armor on the neck formed by the fusion of six individual scutes.
Borealosuchus is an extinct genus of crocodyliforms that lived from the Late Cretaceous to the Eocene in North America. It was named by Christopher Brochu in 1997 for several species that had been assigned to Leidyosuchus. The species assigned to it are: B. sternbergii, the type species, from the Maastrichtian of Colorado, Montana, North Dakota, South Dakota, and Wyoming; B. acutidentatus, from the Paleocene of Saskatchewan; B. formidabilis, from the Paleocene of North Dakota; B. griffithi, from the Paleocene of Alberta; and B. wilsoni, from the Eocene of Wyoming. B. formidabilis is particularly well-known, represented by the remains of many individuals from the Wannagan Creek site in North Dakota. An indeterminate species is known from the Late Cretaceous Demopolis Chalk in Alabama.
Argochampsa is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodilian, related to modern gharials. It lived in the Paleocene of Morocco. Described by Hua and Jouve in 2004, the type species is A. krebsi, with the species named for Bernard Krebs. Argochampsa had a long narrow snout, and appears to have been marine in habits.
Aigialosuchus is an extinct genus of long-snouted crocodylomorph that lived in what is now Sweden during the Campanian stage of the Late Cretaceous period. The name Aigialosuchus comes from the Greek αἰγιαλός (aigialos), meaning "seashore", and σοῦχος (souchus), meaning "crocodile". The genus contains a single species, A. villandensis, described in 1959 by Per Ove Persson based on material recovered from the Kristianstad Basin in southern Sweden.
Eusuchia is a clade of neosuchian crocodylomorphs that first appeared in the Early Cretaceous, which includes modern crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-Pg extinction.
Iharkutosuchus is an extinct genus of basal eusuchian crocodyliform. Its fossils have been found in the Santonian-age Upper Cretaceous Csehbánya Formation in the Bakony Mountains of western Hungary.
Dolichochampsa is an extinct genus of eusuchian crocodylomorph. It is the type genus and only member of the family Dolichochampsidae. Fossils have been found in the Yacoraite Formation of Argentina and the El Molino Formation of Bolivia of Maastrichtian age. It had a distinctive slender snout. Because the material associated with the specimens is so fragmentary, its relationships with other eusuchians remain unknown. Jouve et al. (2020) assigned Dolichochampsa to Gavialoidea, making it the oldest known South American member of this clade.
Eothoracosaurus is an extinct monospecific genus of eusuchian crocodylomorphs found in Eastern United States which existed during the Late Cretaceous period. Eothoracosaurus is considered to belong to an informally named clade called the "thoracosaurs", named after the closely related Thoracosaurus. Thoracosaurs in general were traditionally thought to be related to the modern false gharial, largely because the nasal bones contact the premaxillae, but phylogenetic work starting in the 1990s instead supported affinities within gavialoid exclusive of such forms. Even more recent phylogenetic studies suggest that thoracosaurs might instead be non-crocodilian eusuchians.
Hylaeochampsa is an extinct genus of eusuchian crocodylomorphs. It is known only from a partial skull recovered from Barremian-age rocks of the Lower Cretaceous Vectis Formation of the Isle of Wight. This skull, BMNH R 177, is short and wide, with a eusuchian-like palate and inferred enlarged posterior teeth that would have been suitable for crushing. Hylaochampsa was described by Richard Owen in 1874, with H. vectiana as the type species. It may be the same genus as the slightly older Heterosuchus, inferred to have been of similar evolutionary grade, but there is no overlapping material as Heterosuchus is known only from vertebrae. If the two could be shown to be synonyms, Hylaeochampsa would have priority because it is the older name. Hylaeochampsa is the type genus of the family Hylaeochampsidae, which also includes Iharkutosuchus from the Late Cretaceous of Hungary. James Clark and Mark Norell positioned it as the sister group to Crocodylia. Hylaeochampsa is currently the oldest known unambiguous eusuchian.
Hylaeochampsidae is an extinct family of basal eusuchian crocodylomorphs thought to be closely related to the order Crocodylia.
Thoracosaurus is an extinct genus of long-snouted eusuchian which existed during the Late Cretaceous and Early Paleocene in North America and Europe.
Musturzabalsuchus is an extinct monospecific genus of allodaposuchid eusuchian crocodyliform. The type and only species is Musturzabalsuchus buffetauti.
Gavialoidea is one of three superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial Gavialis gangeticus and the false gharial Tomistoma schlegelii are alive today, with Hanyusuchus having become extinct in the last few centuries.
Brevirostres is a paraphyletic group of crocodilians that included alligatoroids and crocodyloids. Brevirostres are crocodilians with small snouts, and are distinguished from the long-snouted gharials. It is defined phylogenetically as the last common ancestor of Alligator mississippiensis and Crocodylus niloticus and all of its descendants. This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species, and placed the gharials outside the group due to their unique skull structure, and can be shown in the simplified cladogram below:
Allodaposuchidae is an extinct clade of eusuchians that lived in Europe during the Late Cretaceous (Santonian-Maastrichtian).
Lohuecosuchus is an extinct genus of allodaposuchid eusuchian crocodylomorph that lived during the Late Cretaceous in what is now Spain and southern France.
Aprosuchus is a genus of small-bodied Maastrichtian atoposaurid Eusuchian from the Hateg Basin, Romania.