Raphiophoridae
| Raphiophoridae Temporal range: Ordovician to Middle Silurian | |
|---|---|
 | |
| Ampyx nasutus, partially roled, showing the cephalon with genal spines and rapier-like glabellar spine, but hiding most of the thorax and the pygidium | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Trilobita |
| Order: | Asaphida |
| Suborder: | Trinucleina |
| Family: | Raphiophoridae Angelin, 1854 |
| subfamilies | |
see text for genera | |
Raphiophoridae is a family of small to average size trilobites that first occurred at the start of the Ordovician and went extinct at the end of the Middle Silurian. All Raphiophorids are blind, with headshields (or cephalons) that are triangular to subcircular, many carrying long trailing genal spines, a forward directed rapier-like spine on the central raised area (or glabella) or both, with the glabella often inflated and the natural fracture lines (or sutures) of the cephalon coinciding with its margin. Thorax with 7 to 5 segments[1] (except for Taklamakania, Pseudampyxina and Nanshanaspis that have only 3).
Taxonomy
The subfamily Taklamakaniinae was erected to bring together the genera Nanshanaspis, Pseudampyxina and Taklamakania, because they all have only three thorax segments. Analysis of adult anatomy of these genera and larval stages of other raphiophorids showed they most probably developed through paedomorphosis from three different ancestors, and so provide an example of parallel evolution. Nanshanaspis closely resembles young Globampyx, Pseudampyxina strongly looks like juvenile Raymondella, and Taklamakania is almost identical to early stages of Ampyxina. The Taklamakaniinae would therefore be polyphyletic, and are now synonymized with the Raphiophorinae.[2]
Genera
The following genera are assigned to the Raphiophoridae:[1]
Subfamily Raphiophorinae
- Raphiophorus Angelin, 1854
- Ampyx Dalman, 1827
- Ampyxella Dean, 1960
- Ampyxina Ulrich, 1922
- Ampyxinella Koroleva, 1959
- Ampyxoides Whittington, 1965
- Bulbaspis Chugaeva, 1956
- Cnemidopyge Whittard, 1955
- Edmundsonia Cooper, 1953
- Globampyx Fortey, 1975
- Lonchodomas Angelin, 1854
- Mendolaspis Rusconi, 1951
- Miaoposis Lu, ?
- Nanshanaspis Chang & Fan, 1960
- Pseudampyxina Ju, 1983
- Raymondella Reed, 1935
- Rhombampyx Fortey, 1975
- Taklamakania Zhang, 1980
Subfamily Endymioniinae
- Endymionia Billings, 1865
- Anisonotella Whittington, 1965
- Malongullia Webby, Moors & McLean, 1970
- Pytine Fortey, 1975
- Salteria Thomson, 1864
- Typhlokorynetes Shaw, 1966
References
- ↑ 1.0 1.1 Fortey, R.A. (1975). The Ordovician Trilobites of Spitsbergen [II. Asaphidae, Nileidae, Raphiophoridae and Telephinidae of the Valhallfonna Formation]. Norsk Polarinstitutt Skrifter 162. Oslo: Norsk Polarinstitutt.
- ↑ Zhou, Z.; Webby, B.D.; Yuan, W. (1995). "Ordovician trilobites from the Yingan Formation of northwestern Tarim, Xinjiang, northwestern China". Alcheringa: An Australasian Journal of Palaeontology 19 (1): 47–72. doi:10.1080/03115519508619098.