Nuucichthys
From Wikipedia, the free encyclopedia
| Nuucichthys Temporal range: Cambrian, | |
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| Holotype specimen | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Infraphylum: | Agnatha |
| Genus: | †Nuucichthys Lerosey-Aubril & Ortega-Hernández, 2024 |
| Type species | |
| Nuucichthys rhynchocephalus Lerosey-Aubril & Ortega-Hernández, 2024 | |
Nuucichthys (meaning "Núu-ci fish") is an extinct genus of stem-group vertebrates known from the Cambrian (Miaolingian series) Marjum Formation of Utah, United States. The genus contains a single species, N. rhynchocephalus, known from a single individual, representing the first Cambrian vertebrate from the Great Basin region of North America. Nuucichthys provides insights into the diversity of Cambrian vertebrates, which are more rare in Laurentian deposits. Taxonomic studies recover this genus as closely related to other Laurentian stem-vertebrates such as Metaspriggina and Emmonaspis (possible early vertebrate).[1]
The Nuucichthys holotype, UMNH.IP.6084, was discovered in sediments belonging to the House Range of Utah and sent to the Natural History Museum of Utah. The specimen consists of a well preserved individual that is flattened laterally. Although the exact origin of this fossil is uncertain, it most likely comes from the Ptychagnostus punctuosus biozone, located in the middle of the Marjum Formation.[1][2]
The genus name, Nuucichthys, combines "Núu-ci", the name of the Ute tribe meaning "the people", with the Greek word ichthys, meaning "fish". The name refers to the type locality on lands once inhabited by the Ute people. The species name, rhynchocephalus, is derived from the Greek words rhynchos, meaning "beak" or "snout" and kephale, meaning "head", which refers to the projecting region of the front of the head observed in this species.[1]
Description
The holotype specimen of Nuucichthys is around 32.4 millimeters (1.28 inches) long (excluding the eyes and caudal region), and is 7.9 millimeters (0.31 inches) tall. The body of this genus is fusiform in shape, and possess a caudal region lacking any evidence for a fin. The body contained around 40 myomeres that ran along its length, and seem to have shrunk in size after death. The ventral plane of this genus contains a large branchial chamber, and a set of organs which have been interpreted as the liver, and a possible intestine and anus. The caudal region of the body possesses a spiniform structure, which has also been found in animals like Yunnanozoon. By far the most distinguishing feature of this genus is its elongated cephalic region, which helps differentiate it from other Cambrian chordates. This region differentiates from the rest of the body due to the lack of noticeable myomeres, and a sudden change in elevation. This region also possesses a set of paired eyes that are distinct from the various branchial elements. The eyes themselves were well developed camera-type lenses similar to those seen in modern lampreys and Metaspriggina. Like the other known Laurentian stem-vertebrates, this genus seems to lack any sort of fins, and swam in a very different matter to other chordates at the time. This genus also lacks any form of feeding apparatus (or at least ones that would survive fossilization).[1][3][4]
