''Eretmorhipis'' (meaning "oar fan" from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

ερετμον, "oar", and ῥιπίς, "fan") 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 nom ...

hupehsuchia Hupehsuchia is an order of diapsid reptiles closely related to ichthyosaurs. The group was short-lasting, with a temporal range restricted to the late Olenekian age, spanning only a few million years of the Early Triassic. The order gets its na ...

n marine reptiles from the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

of China. It is currently known from two specimens that were discovered in an exposure of the Jialingjiang Formation in

Yuan'an County Yuan'an County () is a county in the west of Hubei province, People's Republic of China. It is under the administration of the prefecture-level city of Yichang. '' Yuanansuchus'', an extinct mastodonsauroid temnospondyl, is named after Yuan'a ...

Hubei Hubei (; ; alternately Hupeh) is a landlocked province of the People's Republic of China, and is part of the Central China region. The name of the province means "north of the lake", referring to its position north of Dongting Lake. The ...

, and referred to the newly named species ''Eretmorhipis carrolldongi'' in 2015. One of those specimens, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

WGSC V26020, had been known since 1991 and consists of the entire skeleton excluding the skull. The second specimen, IVPP V4070, is an impression of the right side of the back half of the skeleton, as well as part of the right fore limb. Two more specimens were discovered in 2018 at the same location, one of which is almost complete and includes the skull.

Description

''Eretmorhipis'' was a relatively small reptile, with the second specimen IVPP V4070 measuring about in total body length. It is unique among hupehsuchians in having manual and

pedal A pedal (from the Latin '' pes'' ''pedis'', "foot") is a lever designed to be operated by foot and may refer to: Computers and other equipment * Footmouse, a foot-operated computer mouse * In medical transcription, a pedal is used to control p ...

digits that radiate in a fan-like shape. Like other hupehsuchians, it has three overlapping layers of armor-like

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 (extinc ...

s over its spine, but the osteoderms of the uppermost layer are significantly larger than they are in other hupehsuchians, each spanning the length of four vertebrae. These upper-layer osteoderms are also widely spaced. The torso of ''Eretmorhipis'' is elongated and encased in a bony tube formed from thickened ribs and

gastralia Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In thes ...

, similar to the bony tube of the hupehsuchian '' Parahupehsuchus'', but less extensive.

Classification

The authors of the 2015 paper that named ''Eretmorhipis'' performed a

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 ...

analysis and found that it was one of the most derived hupehsuchians, forming a clade that they called the Parahupehsuchinae with ''Parahupehsuchus'' and an unnamed polydactylous hupehsuchian. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from their analysis:

References

External links

"And You Thought the Platypus Was Odd"
"Trilobites," NY Times, Jan. 24, 2019 Early Triassic reptiles of Asia Hupehsuchians Fossil taxa described in 2015 Paleontology in Hubei Ichthyosauromorph genera {{triassic-reptile-stub