''Thecachampsa'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

gavialoid 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 ...

crocodylian Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchian ...

, traditionally regarded as a member of the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Tomistominae 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 fres ...

. Fossils have been found from the eastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

in deposits of

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

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.

Description

''Thecachampsa'', like other "tomistomines" of the Oligocene and Miocene, was considerably larger than living crocodilians. Like living

gharial The gharial (''Gavialis gangeticus''), also known as gavial or fish-eating crocodile, is a crocodilian in the family (biology), family Gavialidae and among the longest of all living crocodilians. Mature females are long, and males . Adult males ...

s, it had a long, slender snout. The teeth were long and recurved. Unlike its living relatives, ''Thecachampsa'' was marine, inhabiting

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

and shallow coastal waters. Other marine fossils such as

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

and

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

shells,

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

teeth, and

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

s have been found alongside remains of ''Thecachampsa'' and similar taxa.

Species

In 1852, American paleontologist

Joseph Leidy Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist. Leidy was professor of anatomy at the University of Pennsylvania, later becoming a professor of natural history at Swarth ...

described ''Crocodylus antiquus'' from Miocene deposits in the Lee family's ancestral home in Virginia. The holotype was a tooth found in the

Calvert Formation The Calvert Formation is a Formation (geology), geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene, Miocene epoch of the Neogene Period (geology), period. It is one of the three ...

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

. Leidy also described additional material including several teeth and

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amph ...

s, two

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e, a rib, and an

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

phalanx or claw bone. The new genus ''Thecachampsa'' was erected by

Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontology, paleontologist, comparative anatomy, comparative anatomist, herpetology, herpetologist, and ichthyology, ichthyologist. Born to a wealthy Quaker fam ...

in 1867, containing two species, ''T. sericodon'' and ''T. contusor'', both also based on teeth, but no type species was designated. Cope (1882) designated ''T. sericodon'' as the ''Thecachampsa'' type species. ''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). Crocodilian material found from Miocene deposits in the eastern United States has often been attributed to ''Thecachampsa'', even isolated teeth with few distinguishable features. 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. That year,

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

named another species of ''Thecachampsa'', "T. squankensis", after the place of its discovery, Squankum,

New Jersey New Jersey is a U.S. state, state located in both the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. Located at the geographic hub of the urban area, heavily urbanized Northeas ...

, but that name is a ''nomen nudum'' because Marsh provided no description, diagnosis, or type specimen. Cope named a new species, ''T. fastigiata'', in 1870 as a reassignment of ''Crocodylus fastigiatus'', named by Leidy in 1852. 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 ''Crocodylus'' is a genus of true crocodiles in the family Crocodylidae. Taxonomy The Genus, generic name, ''Crocodylus'', was proposed by Josephus Nicolaus Laurenti in 1768. ''Crocodylus'' contains 13–14 extant taxon, extant (living) species ...

'' in 1973, but has since been regarded as valid. A clear phylogenetic distinction between North American ''

Gavialosuchus ''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. Taxonomy The t ...

'' and the type species of ''

'', '' Gavialosuchus eggenburgensis'' Toula and Kail 1885 from the Miocene of Austria, was clear once they were analyzed together in phylogenetic analyses. In 2001, A.C. Myrick synonymized '' Gavialosuchus americanus'', another "tomistomine" from the eastern United States, with ''T. antiqua''. Myrick also synonymized ''

Tomistoma lusitanicum ''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 (''Tomistoma schlegelii''), as well ...

'', a "tomistomine" from

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

, with ''Thecachampsa'', though this has not been supported by subsequent analyses that clearly distinguish them. 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 ''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 (''Tomistoma schlegelii''), as well ...

americanus'' in 1915, with remains having been found from the

Kirkwood Formation The Kirkwood Formation is a geological formation found in the Eastern and Western Cape provinces in South Africa. It is one of the four formations found within the Uitenhage Group of the Algoa Basin – its type locality – and in the neighbour ...

, the

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

, the Chesapeake Group of

, and the

Pungo River The Pungo River is a river in eastern North Carolina, United States. It originally began in the Great Dismal Swamp in Washington County, North Carolina; the upper part of the river has since been supplanted by the Pungo River Canal, dug in the 1 ...

and

Yorktown Formation The Yorktown Formation is a mapped bedrock unit in the Coastal Plain of Maryland, Virginia, North Carolina and South Carolina. It is overconsolidated and highly fossiliferous. Description The Yorktown is composed largely of overconsolidated san ...

s of

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

. Remains have also been found from

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

, and, more recently,

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

. Fossils of the species are present in deposits that range in age from the late

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

to the early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58δ¹⁸O and δ¹³C measurements suggest that ''T. americana'' primarily fed on marine prey, in contrast to sympatric ''

Alligator An alligator, or colloquially gator, is a large reptile in the genus ''Alligator'' of the Family (biology), family Alligatoridae in the Order (biology), order Crocodilia. The two Extant taxon, extant species are the American alligator (''A. mis ...

'' that ate freshwater prey.

References

{{Taxonbar, from=Q7777625, from2=Q112844980, from3=Q112845050, from4=Q112845091 Crocodilia Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Oligocene crocodylomorphs Oligocene reptiles of North America Taxa named by Edward Drinker Cope