Eretmorhipis
Temporal range: Early Triassic
The holotype specimen of Eretmorhipis carrolldongi, WGSC V26020
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: †Hupehsuchia
Family: †Hupehsuchidae
Genus: †Eretmorhipis
Chen et al., 2015
Type species
†Eretmorhipis carrolldongi
Chen et al., 2015

Eretmorhipis (meaning "oar fan" from the Greek ερετμον, "oar", and ῥιπίς, "fan") is an extinct genus of hupehsuchian marine reptiles from the Early Triassic of China. It is currently known from two specimens that were discovered in an exposure of the Jialingjiang Formation in Yuan'an County, Hubei, and referred to the newly named species Eretmorhipis carrolldongi in 2015.

Eretmorhipis carrolldongi is noted for its exceptionally small eyes relative to the body, platypus-like snout, and plates on its back "like a stegosaurus."[1]

One of those specimens, the holotype 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.[2]

Description

Nearly complete assigned specimen

Eretmorhipis was a relatively small reptile, with the second specimen IVPP V4070 measuring about 1 m (3.3 ft) in total body length.[3][4] It is unique among hupehsuchians in having manual and pedal digits that radiate in a fan-like shape. Like other hupehsuchians, it has three overlapping layers of armor-like osteoderms 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, similar to the bony tube of the hupehsuchian Parahupehsuchus, but less extensive.[5]

Discovery

The first specimen, discovered in the 1991, was missing a head. The next, more complete, fossils were found in 2015 by Wong Cheng of the Wuhan Center of China Geological Survey.[1]

University of California, Davis paleobiologist Ryosuke Motani told The New York Times that the animal's odd features initially stunned him: “When I first saw it, I just said ‘What?!’ and didn’t speak for a while.”[1]

Classification

The authors of the 2015 paper that named Eretmorhipis performed a phylogenetic 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 from their analysis:[5]

Hovasaurus

Cartorhynchus

Chaohusaurus

Hupehsuchia

Nanchangosaurus

Eohupehsuchus

Hupehsuchidae

Hupehsuchus

Parahupehsuchinae

Parahupehsuchus

Polydactylous hupehsuchian

Eretmorhipis

References

  1. 1 2 3 Fleur, Nicholas St (2019-01-24). "And You Thought the Platypus Was Odd". The New York Times. ISSN 0362-4331. Retrieved 2023-06-20.
  2. ↑ Cheng, Long; Motani, Ryosuke; Jiang, Da-Yong; Yan, Chun-bo; Tintori, Andrea; Rieppel, Olivier (2019). "Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection". Scientific Reports. 9 (1): 152. Bibcode:2019NatSR...9..152C. doi:10.1038/s41598-018-37754-6. PMC 6345829. PMID 30679783.
  3. ↑ Chen, X.-H.; Motani, R.; Cheng, L.; Jiang, D.-Y.; Rieppel, O. (2014). Farke, Andrew A. (ed.). "A Small Short-Necked Hupehsuchian from the Lower Triassic of Hubei Province, China". PLOS ONE. 9 (12): e115244. Bibcode:2014PLoSO...9k5244C. doi:10.1371/journal.pone.0115244. PMC 4269458. PMID 25517113.
  4. ↑ Li, Qiang; Liu, Jun (2020). "An Early Triassic sauropterygian and associated fauna from South China provide insights into Triassic ecosystem health". Communications Biology. 3 (1). 63. doi:10.1038/s42003-020-0778-7. PMC 7012838. PMID 32047220.
  5. 1 2 Xiao-hong Chen; Ryosuke Motani; Long Cheng; Da-yong Jiang; Olivier Rieppel (May 27, 2015). "A New Specimen of Carroll's Mystery Hupehsuchian from the Lower Triassic of China". PLOS ONE. 10 (5): e0126024. Bibcode:2015PLoSO..1026024C. doi:10.1371/journal.pone.0126024. PMC 4446317. PMID 26017585.


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