Tricrepicephalus
| Tricrepicephalus Temporal range: Dresbachian | |
|---|---|
 | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Trilobita |
| Order: | Ptychopariida |
| Superfamily: | Crepicephalacea |
| Family: | Tricrepicephalidae |
| Genus: | Tricrepicephalus Kobayashi, 1935 |
| species | |
| |
| Synonyms | |
|
Paracrepicephalus | |
Tricrepicephalus is an extinct genus of ptychopariid trilobites of the family Tricrepicephalidae with species of average size. Its species lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian Period. Fossils of Tricrepicephalus are widespread in Late Cambrian deposits in North America, but is also known from one location in South-America. Tricrepicephalus has a inverted egg-shaped exoskeleton, with three characteristic pits in the fold that parallels the margin of the headshield just in front of the central raised area. The articulating middle part of the body has 12 segments and the tailshield carries two long, tubular, curved pygidial spines that are reminiscent of earwig's pincers that rise backwards from the plain of the body at approximately 30°.[1]
Differences with Meteoraspis
Meteoraspis has two equally prominent pits in the anterior border furrow, a much more vaulted cephalon, with short spines reaching to about the second thorax segment, 13 thorax segments and two flat, shark tooth shaped, widely spaced spines on the pygidium.[1]
Reassigned species
- T. metra = Meteoraspis metra[1]
Distribution
- T. asiaticus occurs in the Upper Cambrian of China (Guzhangian, Blackwelderia zone, Chefu Formation, Yangweizhou-Jimachong)[2]
- T. arcuatus has been found in the Upper Cambrian of the United States (Merioneth, Warrior Formation, Highway No. 322 near Waddle, Bed 13.3, Centre County, Pennsylvania, 40.8° N, 77.9° W)[3]
- T. texanus is known from the Upper Cambrian of Canada (Dresbachian, Rabbitkettle Formation, southern Mackenzie Mountains, northwest Canada) and the United States (Dresbachian, Crepicephalus trilobite zone, Deadwood Formation, Whitewood Creek in Lead County, South Dakota, 44.3° N, 103.8° W).[4]
- T. tripunctatus is present in the Upper Cambrian of the United States (Dresbachian, Crepicephalus trilobite zone, lower Member of the Deadwood Formation, Little Elk Creek County, South Dakota, 44.3° N, 103.6° W).[4]
Ecology
T. tripunctatus occurs together with trilobite species from the genera Coosia, Crepicephalus, Kingstonia, Pseudagnostina, and Coosina.[5]
References
- ↑ 1.0 1.1 1.2 Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O249–O250. ISBN 0-8137-3015-5.
- ↑ Yuan, J.L.; Yin, G.Z. (1998). "New polymerid trilobites from the Chefu Formation in early Late Cambrian of eastern Guizhou". Acta Palaeontologica Sinica 37 (2): 137–172. cited in Uta Merkel. "Yangweizhou-Jimachong, Blackwelderia zone". Fossilworks. Retrieved 2014-12-14.
- ↑ Tasch, P. . (1951). "Fauna and paleoecology of the Upper Cambrian Warrior Formation of central Pennsylvania". Journal of Paleontology 25 (3): 275–306. cited in Uta Merkel. "Highway No. 322 near Waddle, Bed 13.3". Fossilworks. Retrieved 2014-12-14.
- ↑ 4.0 4.1 Stitt, J.H.; Perfetta, P.J. (2000). "Trilobites, Biostratigraphy, and Lithostratigraphy of the Crepicephalus and Aphelaspis zones, Lower Deadwood formation (Marjuman and Steptoean Stages, Upper Cambrian), Black Hills, South Dakota". Journal of Paleontology 74 (2): 199–223. doi:10.1666/0022-3360(2000)074<0199:tbalot>2.0.co;2. cited in Kyle Straub. "High School Sample 34". Fossilworks. Retrieved 2014-12-14.
- ↑ Stitt, J.H.; Perfetta, P.J. (2000). "Trilobites, Biostratigraphy, and Lithostratigraphy of the Crepicephalus and Aphelaspis zones, Lower Deadwood formation (Marjuman and Steptoean Stages, Upper Cambrian), Black Hills, South Dakota". Journal of Paleontology 74 (2): 199–223. doi:10.1666/0022-3360(2000)074<0199:tbalot>2.0.co;2.