''Spathorhynchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

amphisbaenia Amphisbaenia (called amphisbaenians or worm lizards) is a group of usually legless squamates, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...

ns or worm lizards that existed from the

Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

to the

Early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...

in what is now Wyoming. It includes two species, the

type species In 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 species that contains the biological type specimen ...

''S. fossorium'', named in 1973 from the Middle Eocene Bridger and

Wind River Formation The Wind River Formation is a geologic formation in Wyoming. It preserves fossils dating back to the Paleogene period. A recent study by Stanford suggests that fracking has contaminated the entire ground water resource in the basin. Fossil conten ...

s, and the species ''S. natronicus'', named in 1977 from the Lower Oligocene

White River Formation The White River Formation is a geologic formation of the Paleogene Period, in the northern Great Plains and central Rocky Mountains, within the United States. It has been found in northeastern Colorado, Dawes County in western Nebraska, Badlands ...

. ''Spathorhynchus'' belongs to the family

Rhineuridae Rhineuridae is a family of amphisbaenians (commonly called worm lizards) that includes one living genus and species, ''Rhineura floridana'', as well as many extinct species belonging to both ''Rhineura'' and several extinct genera. The living ''R ...

, which includes many other extinct species that ranged across North America at various times in the Cenozoic but only has one surviving member, ''

Rhineura floridana ''Rhineura floridana'', known commonly as the Florida worm lizard, graveyard snake, Goin CJ, Goin OB, Zug GR (1978). ''Introduction to Herpetology, Third Edition''. San Francisco: W.H. Freeman and Company. xi + 378 pp. . (''Rhineura floridana ...

'', from Florida. ''Spathorhynchus'' differs from all other rhineurids except ''

Dyticonastis ''Dyticonastis'' is an extinct genus of amphisbaenians, or worm lizards, that includes a single species, ''Dyticonastis rensbergeri'', that lived during the late Oligocene and early Miocene in what is now Oregon. Fossils of the species come from ...

'' from the

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

of Oregon in having a slightly widened, spatula-shaped snout tip with a low angle of about 30 degrees. The two taxa may be closely related, having evolved in isolation in western North America after the formation of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

separated them from rhineurids further east.

References

Amphisbaenians Eocene lepidosaurs Oligocene lepidosaurs Eocene reptiles of North America Oligocene reptiles of North America Prehistoric lizard genera Eocene genus first appearances Rupelian genus extinctions Fossil taxa described in 1973 {{paleo-lizard-stub