''Omosaurus'' is a dubious

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 ...

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 ...

crurotarsan

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

, possibly a

phytosaur Phytosaurs (Φυτόσαυροι in Greek, meaning 'plant lizard') are an extinct group of large, mostly semiaquatic Late Triassic archosauriform or basal archosaurian reptiles. Phytosaurs belong to the order Phytosauria and are sometimes ref ...

, from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

(

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

) 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 ...

. Only scant remains are known, which makes ''Omosaurus'' hard to classify. The type, and only species, ''Omosaurus perplexus'', was named and described in 1856 by

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 ...

Discovery and naming

In the middle of the nineteenth century,

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

Professor

Ebenezer Emmons Ebenezer Emmons (May 16, 1799October 1, 1863), was an American geologist whose work includes the naming of the Adirondack Mountains in New York as well as a first ascent of Mount Marcy. Early life Emmons was born at Middlefield, Massachusetts, ...

discovered several reptilian teeth in the

colliery Coal mining is the process of extracting coal from the ground or from a mine. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extra ...

of the Chatham company in

. In 1856, the fossils in his collection were described by

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

. Leidy combined the teeth with some vertebrae and ribs; adding to them an

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 ...

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...

found in the same strata by Professor Michael Tuomey, he named the whole ''Omosaurus perplexus''.J. Leidy, (1856), "Notice of remains of extinct vertebrated animals discovered by Professor E. Emmons", ''Proceedings of the Academy of Natural Sciences of Philadelphia'' 8: 255-257 Leidy provided no

etymology Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

; the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

suggests he was intrigued by the "intricate" find. The generic name might be derived from the Greek ὠμός, ''omos'', "rough", perhaps in reference to the rough surface of the scute or to the "savage" nature of a carnivorous reptile. Today, all

syntype In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part o ...

s are lost.

Description

The teeth were described as being rather straight, slightly curved inwards, conical and pointed with a length of up to one inch. They had two edges at the inside and a D-shaped cross-section with the convex part positioned at the outer side. The surface of the teeth was smooth with little wrinkles, running vertically at the inside and horizontally at the outside. The vertebrae were amphicoelous and constricted at the waist, with a length of about three centimetres and somewhat taller than wide in cross-section. The scute was ornamented with a fan-shaped pattern of splitting ridges.

Phylogeny

Leidy himself believed ''Omosaurus'' to be a marine reptile, probably a

plesiosaur The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...

, suspecting the remains were referable to some already named genus. In 1902, Frederick Augustus Lucas recognised the fossils as "crocodilian" in nature and placed ''Omosaurus'' in the

Crocodilia 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 pseudosuchia ...

. At the same time he affirmed the priority over ''Omosaurus'' (

Owen Owen may refer to: People and fictional characters * Owen (name), including a list of people and fictional characters with the given name or surname Places United States * Owen, Missouri, a ghost town * Owen, Wisconsin * Owen County, Indiana ...

1875), which stegosaur was by him renamed to '' Dacentrurus''. Today, ''Omosaurus'' is commonly listed as a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

'', a possible member of the

Phytosauria Phytosaurs (Φυτόσαυροι in greek language, Greek, meaning 'plant lizard') are an extinct group of large, mostly semiaquatic Late Triassic archosauriform or Basal (phylogenetics), basal archosaurian reptiles. Phytosaurs belong to the ord ...

References

{{Taxonbar, from=Q1924922 Fossil taxa described in 1856 Phytosauria Late Triassic reptiles of North America Nomina dubia Prehistoric reptile genera