Thecachampsa Temporal range: Miocene, | |
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T. carolinense skeleton | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauromorpha |
Clade: | Archosauriformes |
Order: | Crocodilia |
Superfamily: | Gavialoidea |
Family: | Gavialidae |
Subfamily: | Tomistominae |
Genus: | † Thecachampsa Cope, 1867 |
Species | |
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Thecachampsa is an extinct genus of gavialoid crocodylian, traditionally regarded as a member of the subfamily Tomistominae. [2] Fossils have been found from the eastern United States in deposits of Miocene age. Those named in the 19th century were distinguished primarily by the shape of their teeth, and have since been combined with T. antiquus. More recently erected species were reassigned from other genera, although their assignment to Thecachampsa has since been questioned.
Thecachampsa, like other "tomistomines" of the Oligocene and Miocene, was considerably larger than living crocodilians. Like living gharials, it had a long, slender snout. The teeth were long and recurved. Unlike its living relatives, Thecachampsa was marine, inhabiting estuaries and shallow coastal waters. Other marine fossils such as sea snail and bivalve shells, shark teeth, and barnacles have been found alongside remains of Thecachampsa and similar taxa. [3]
In 1852, American paleontologist Joseph Leidy described Crocodylus antiquus from Miocene deposits in the Lee family's ancestral home in Virginia. [4] The holotype was a tooth found in the Calvert Formation of Virginia. Leidy also described additional material including several teeth and osteoderms, two vertebrae, a rib, and an ungual phalanx or claw bone. The new genus Thecachampsa was erected by Edward Drinker Cope in 1867, containing two species, T. sericodon and T. contusor, both also based on teeth, but no type species was designated. [5] Cope (1882) designated T. sericodon as the Thecachampsa type species. [6] T. sericodon was distinguished from T. antiqua by its slender, curved teeth, each with a sharp edge near the base of the posterior margin (T. antiqua only possessed sharp edges along a small area near the tip of the posterior margin). [3]
Crocodilian material found from Miocene deposits in the eastern United States has often been attributed to Thecachampsa, even isolated teeth with few distinguishable features. [7] In 1869, Cope named a fourth species, T. sicaria, from a jaw fragment and a dorsal vertebra. Unlike those of other species, the teeth of T. sicaria were lenticular (lens-shaped) in cross section with sharp cutting edges. [3] That year, Othniel Charles Marsh named another species of Thecachampsa, "T. squankensis", after the place of its discovery, Squankum, New Jersey, but that name is a nomen nudum because Marsh provided no description, diagnosis, or type specimen. [8] Cope named a new species, T. fastigiata, in 1870 as a reassignment of Crocodylus fastigiatus, named by Leidy in 1852. [9] These species were distinguished from one another primarily by differences in the shape of the teeth, the most common material found. The genus was synonymized with Crocodylus in 1973, but has since been regarded as valid. [10]
A clear phylogenetic distinction between North American Gavialosuchus and the type species of Gavialosuchus , Gavialosuchus eggenburgensis Toula and Kail 1885 [11] from the Miocene of Austria, was clear once they were analyzed together in phylogenetic analyses. [12] [13] [14] [15] In 2001, A.C. Myrick synonymized Gavialosuchus americanus , another "tomistomine" from the eastern United States, with T. antiqua. [16] Myrick also synonymized Tomistoma lusitanicum , a "tomistomine" from Portugal, with Thecachampsa, though this has not been supported by subsequent analyses that clearly distinguish them. [13] [14] [15] [17] The genus name Thecachampsa has priority over the other two, as it was erected earlier. A geologically younger species was first described from Florida as Tomistoma americanus in 1915, with remains having been found from the Kirkwood Formation in New Jersey, the Calvert Formation in Maryland, the Chesapeake Group of Virginia, and the Pungo River and Yorktown Formations of North Carolina. Remains have also been found from Florida, California, Baja California, and, more recently, Costa Rica. Fossils of the species are present in deposits that range in age from the late Early Miocene to the early Pliocene. [18] A few studies such as that of Jouve et al. (2008) have kept the species within Gavialosuchus, leaving T. antiqua as the only species within Thecachampsa, [19] though they didn't test Thecachampsa antiqua in their phylogenetic analysis, and most other analyses recover a clade including all North American forms that had previously been referred Gavialosuchus with a broad phylogenetic separation between them and G. eggenburgensis. [14] [15] [20] [21]
The cladogram below follows from Brochu and Storrs (2012).
Crocodyloidea |
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In addition to reassigning G. americanus and G. carolinensis to Thecachampsa, Myrick combined all previously named species of Thecachampsa in a single species, with the oldest name being T. antiqua. The different tooth shapes that distinguished the species were considered variations in the dentition of a single species. [16] However, the variation in dentition could only be seen in complete skulls, all of which had been referred to Gavialosuchus before the genus was synonymized with Thecachampsa.
Weems (2018) agreed with Piras et al. (2007) and Brochu & Storrs (2012) that Tomistoma americana and Gavialosuchus carolinensis belong to Thecachampsa rather than Gavialosuchus, but treated sericodon and antiqua as distinct species rather than one species, and suggested that the americanus holotype is conspecific with T. sericodon, making T. americana a synonym of T. sericodon.
Most subsequent analyses have not accepted these suggestions based on clear differences between T. americana and T. antiqua and the lack of differences not explained by taphonomy between T. antiqua and T. sericodon.
Gavialinae is a subfamily of large semiaquatic crocodilian reptiles, resembling crocodiles, but with much thinner snouts. Gavialinae is one of the two major subfamilies within the family Gavialidae - the other being the subfamily Tomistominae, which contains the false gharial and extinct relatives.
Gavialidae is a family of large semiaquatic crocodilians with elongated, narrow snouts. Gavialidae consists of two living species, the gharial and the false gharial, both occurring in Asia. Many extinct members are known from a broader range, including the recently extinct Hanyusuchus. Gavialids are generally regarded as lacking the jaw strength to capture the large mammalian prey favoured by crocodiles and alligators of similar size so their thin snout is best used to catch fish, however the false gharial has been found to have a generalist diet with mature adults preying upon larger vertebrates, such as ungulates.
Tomistoma is a genus of gavialid crocodilians. They are noted for their long narrow snouts used to catch fish, similar to the gharial. Tomistoma contains one extant (living) member, the false gharial, as well as potentially several extinct species: T. cairense, T. lusitanicum and T. coppensi. Previously assigned extinct species known from fossils are reclassified as different genera such as Eogavialis, Toyotamaphimeia and Sutekhsuchus.
Toyotamaphimeia is a genus of extinct gavialid crocodylian which lived in Japan and Taiwan during the Middle Pleistocene. A specimen recovered in 1964 at Osaka University during the construction of a new science building has been dated to around 430–380 thousand years old based on the stratum in which it was found. Toyotamaphimeia was a fairly large crocodylian measuring approximately 6.3–7.3 metres (21–24 ft) long. Two species are named, T. machikanensis from Japan and T. taiwanicus from Taiwan, both originally described as members of the genus Tomistoma.
Gavialosuchus is an extinct genus of gavialoid crocodylian from the early Miocene of Europe. Currently only one species is recognized, as a few other species of Gavialosuchus have since been reclassified to other genera.
Dollosuchoides, colloquially known as the Crocodile of Maransart, is an extinct monospecific genus of gavialoid crocodilian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found in the Brussel Formation of Maransart, Belgium and date back to the middle Eocene.
Eogavialis is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodylian. It superficially resembles Tomistoma schlegelii, the extant false gharial, and consequently material from the genus was originally referred to Tomistoma. Indeed, it was not until 1982 that the name Eogavialis was constructed after it was realised that the specimens were from a more basal form.
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.
Euthecodon is an extinct genus of long-snouted crocodile. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya, Ethiopia, and Libya. Although superficially resembling that of gharials, the long snout was a trait developed independently from that of other crocodilians and suggests a diet of primarily fish. Euthecodon coexisted with a wide range of other crocodiles in the areas it inhabited before eventually going extinct during the Pleistocene.
Kentisuchus is an extinct genus of gavialoid crocodylian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found from England and France that date back to the early Eocene. The genus has also been recorded from Ukraine, but it unclear whether specimens from Ukraine are referable to Kentisuchus.
Maroccosuchus zennaroi is an extinct gavialoid crocodylian from the Early Eocene of Morocco, traditionally regarded as a member of the subfamily Tomistominae.
Paratomistoma is an extinct monospecific genus of gavialoid crocodylian. It is based on the holotype specimen CGM 42188, a partial posterior skull and lower jaw discovered at Wadi Hitan, Egypt, in Middle Eocene-age rocks of the Gehannam Formation. The skull is unfused but considered morphologically mature. Paratomistoma was named in 2000 by Christopher Brochu and Philip Gingerich; the type species is P. courti in honor of Nicholas Court, who found CGM 42188. They performed a phylogenetic analysis and found Paratomistoma to be a derived member of Tomistominae, related to the false gharial. It may have been a marine or coastal crocodilian.
Penghusuchus is an extinct genus of gavialid crocodylian. It is known from a skeleton found in Middle to Upper Miocene rocks of Penghu Island, off Taiwan. The taxon was described in 2009 by Shan and colleagues; the type species is P. pani. It may be related to two other fossil Asian gavialids: Toyotamaphimeia machikanensis of Japan and Hanyusuchus sinensis of South China. It was a medium-sized gavialid with an estimated total length of 4.5 metres (15 ft).
Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in the Miocene of South America. However, "Ikanogavialis" papuensis may have survived more recently, into the Late Pleistocene/Holocene. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus and Aktiogavialis, although a 2018 study indicates that the group might be paraphyletic and rather an evolutionary grade towards the gharial.
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.
Tomistominae is a subfamily of crocodylians that includes one living species, the false gharial. Many more extinct species are known, extending the range of the subfamily back to the Eocene epoch. In contrast to the false gharial, which is a freshwater species that lives only in southeast Asia, extinct tomistomines had a global distribution and lived in estuaries and along coastlines.
Brochuchus is an extinct genus of crocodile known from the Early Miocene Hiwegi Formation of Rusinga Island in Lake Victoria, Kenya; it was originally named as a species of Crocodylus. It contains two species, B. parvidens and B. pigotti. Brochuchus belongs to the family Crocodylidae, which includes all living crocodiles. The closest living relative of Brochuchus is Osteolaemus, the dwarf crocodile. Compared to Osteolaemus, which has a small body and blunt snout, Brochuchus has a more generalized crocodylid anatomy. Brochuchus is characterized by a flat and relatively narrow skull, and although it is larger than Osteolaemus it is smaller than most other crocodylids. It has two prominent bumps on the surface of its snout.
Tomistoma cairense is an extinct species of gavialoid crocodilian from the Lutetian stage of the Eocene era. It lived in North East Africa, especially Egypt. Remains of T. cairense have been found in the Mokattam Formation, in Mokattam, Egypt. Tomistoma cairense did not have a Maxilla process within their lacrimal gland, whereas all extant (living) crocodilians do.
Maomingosuchus is an extinct genus of gavialoid crocodylian from Late Eocene of Southeast Asia. It was discovered in Priabonian-aged deposits of China and possibly also Thailand. The type species, originally Tomistoma petrolica, was named in 1958 and was redescribed as Maomingosuchus in 2017. A second species, Maomingosuchus acutirostris, was described in 2022 from middle-upper Eocence deposits of the Na Duong Basin in northern Vietnam. It is proposed to be a basal member of Gavialoidea, or alternatively within the family Tomistominae. It was a relatively small gavialoid with an estimated total length of 3–3.5 metres (9.8–11.5 ft).
Sutekhsuchus is a species of gavialine crocodilian from the Miocene of Libya and Egypt. While this species was originally described as a species of the genus Tomistoma, which includes the modern false gharial, later studies have shown that it was actually a much more derived gavialoid closely related to the Kenyan Eogavialis andrewsi. Since it initially "decieved" paleontologists, it was named for the Egyptian "god of deception" Sutekh. It once inhabited the slow-moving rivers, estuaries and lagoons of what is now Gebel Zelten and Wadi Moghra, environments it shared with a variety of other crocodilians including the narrow-snouted Euthecodon and the robust Rimasuchus. Only a single species is currently assigned to Sutekhsuchus, the type species S. dowsoni.