''Eurycleidus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of large-bodied rhomaleosaurid known from the

Early Jurassic The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma ...

period (most likely earliest

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triassi ...

stage) of the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

. It contains a single species, ''E. arcuatus''. Like other plesiosaurs, ''Eurycleidus'' probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward stroke for fast swimming.

Phylogeny

Most

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses find the type species of the genus, ''Eurycleidus arcuatus'', to be a relatively

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

rhomaleosaurid. A second species, ''E. megacephalus'' (Stutchbury, 1846 riginally ''Rhomaleosaurus megacephalus''">Rhomaleosaurus.html" ;"title="riginally ''Rhomaleosaurus">riginally ''Rhomaleosaurus megacephalus'', was reassigned to this genus by Smith (2007). However, most analyses find ''E. megacephalus'' to represent an unnamed genus, which is distinct from both ''Eurycleidus'' and ''Rhomaleosaurus''. ''E. megacephalus'' was moved to its own genus ''Atychodracon'' by Adam Smith in 2015. The cladogram below shows ''E. arcuatus'' phylogenetic position among other plesiosaurs following Benson ''et al.'' (2012).

References

{{Taxonbar, from=Q3616157 Rhomaleosaurids Early Jurassic plesiosaurs of Europe Fossil taxa described in 1922 Taxa named by Charles William Andrews Sauropterygian genera

Phylogeny

See also

References