''Thoracosaurus'' (chest lizard) 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 ...

of long-snouted

eusuchia Eusuchia is a clade of neosuchian Crocodylomorpha, crocodylomorphs that first appeared in the Early Cretaceous, which includes modern Crocodilia, crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survi ...

n which existed during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

and

Early Paleocene The Danian is the oldest age (geology), age or lowest stage (stratigraphy), stage of the Paleocene Epoch or series (stratigraphy), Series, of the Paleogene Period or system (stratigraphy), System, and of the Cenozoic Era or Erathem. The beginnin ...

in North America and Europe.

Taxonomy

''Thoracosaurus'' had traditionally been thought to be related to the modern

false gharial The false gharial (''Tomistoma schlegelii''), also known by the names Malayan gharial, Sunda gharial and tomistoma is a freshwater crocodilian of the Family (biology), family Gavialidae native to Peninsular Malaysia, Borneo, Sumatra and Java. It ...

, largely because the nasal bones contact the premaxillae.

Phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

work starting in the 1990s instead supported affinities within Gavialoidea exclusive of such forms, although a 2018 tip dating study simultaneously using morphological, molecular (

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The ...

), and

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

(

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

age) data suggests that it might have been a non-

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 ...

eusuchian. The genus contains the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

''Thoracosaurus neocesariensis'' in North America, and what is either ''Thoracosaurus isorhynchus'' or ''Thoracosaurus macrorhynchus'' from Europe; a recent review argues that ''T. macrorhynchus'' is a junior

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''T. isorhynchus,'' but it is unclear whether the type of ''T. isorhynchus'' allows differentiation of European and North American ''Thoracosaurus;'' if not, then ''T. isorhynchus'' would be 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 number of species have been referred to this genus, but most are dubious.

Ecology

It is thought to have inhabited marine environments.

Gallery

Thoracosaurus macrorhynchus - Maastricht.jpg, ''Thoracosaurus macrorhynchus'' skull at the Naturalis Museum in

Leiden Leiden ( ; ; in English language, English and Archaism, archaic Dutch language, Dutch also Leyden) is a List of cities in the Netherlands by province, city and List of municipalities of the Netherlands, municipality in the Provinces of the Nethe ...

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

Image:Thoracosaurus.jpg, ''Thoracosaurus sp.'' teeth at the Geological Museum, Copenhagen File:Thoracosaurus EFM.jpg, ''Thoracosaurus neocesariensis'' mandible at the Edelman Fossil Museum

References

{{Taxonbar, from=Q2408250, from2=Q41168408 Neosuchia Late Cretaceous crocodylomorphs Paleocene crocodylomorphs Late Cretaceous first appearances Cretaceous–Paleogene boundary Paleocene extinctions Cretaceous reptiles of North America Paleocene reptiles of North America Hell Creek fauna Fossil taxa described in 1852 Taxa named by Joseph Leidy Prehistoric pseudosuchian genera