Raphiophoridae

Raphiophoridae; Temporal range: Ordovician to Middle Silurian PreꞒ Ꞓ O S D C P T J K Pg N
	Curled Ampyx nasutus showing the cephalon, genal spines & glabellar spine
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita
Order:	†Asaphida
Superfamily:	†Trinucleioidea
Family:	†Raphiophoridae; Angelin, 1854
Subfamilies
	Raphiophorinae Angelin, 1854; Endymioniinae Raymond, 1920; see text for genera
Synonyms
	Subfamilies Ampyxininae; Ampyxinellinae; Taklamakaniinae; Typhlokorynetidae; ;

Raphiophoridae is a family of small to average-sized trilobites that first occurred at the start of the Ordovician and became extinct at the end of the Middle Silurian.

Anatomy

All raphiophorids are blind, with headshields (or cephalons) that are triangular to subcircular, and many carry 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. The thorax typically has five to seven segments^[1] (except for the genera Taklamakania, Pseudampyxina, Nanshanaspis, and Kongqiangheia, which have only 3). As mentioned before, all raphiophorids are blind. Many, if not most, genera have no eyes whatsoever, though a few, such as Lehnertia, have vestigial tubercles that correspond to the compound eyes of their ancestors.

Distribution

Raphiophoridae currently includes two officially recognized subfamilies. The nominal subfamily Raphiophorinae originated from the Upper Tremadocian and died out during the Lower Ludlow, and has 217 species assigned to it divided over 26 genera. The subfamily Endymioniinae occurred from the Floian or possibly from the Lower Tremadocian to the Upper Katian and contains 36 species in 13 genera. The time of the first occurrence depends on whether the inadequately known monotypic genus Typhlokorynetes from the Lower Tremadocian of Laurentia is considered an endymioniin. Raphiophorids are generally found in deep-water sediments, and have a cosmopolitan distribution from the Floian to the Ordovician–Silurian extinction events with diversity peaking from the Darriwilian to the Sandbian. Raphiophorus survived into the Silurian.^[2]

Taxonomy

The subfamily Taklamakaniinae was erected to bring together the genera Nanshanaspis, Pseudampyxina, and Taklamakania, (and then, later, Kongqiangheia) on the basis that they all have only three thoracic 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, 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. Since the three genera of the Taklamakaniinae have been demonstrated to be unrelated to each other, this subfamily is regarded as polyphyletic, and has been synonymized with the Raphiophorinae.^[3]

Genera

These genera are assigned to the Raphiophoridae:^[1]

Subfamily Raphiophorinae

Raphiophorus Angelin, 1854
Ampyx Dalman, 1827
Ampyxella Dean, 1960
Ampyxina Ulrich, 1922
Ampyxoides Whittington, 1965
Bulbaspis Chugaeva, 1956
Cnemidopyge Whittard, 1955
Edmundsonia Cooper, 1953
Globampyx Fortey, 1975
Kongqiangheia
Lonchodomas Angelin, 1854
Mendolaspis Rusconi, 1951
Nanshanaspis Chang & Fan, 1960
Pseudampyxina Ju, 1983
Raymondella Reed, 1935
Rhombampyx Fortey, 1975
Taklamakania Zhang, 1980

Subfamily Endymioniinae

Endymionia Billings, 1865
Ampyxinella Koroleva, 1959
Ampyxinops Zhang 1979
Anisonotella Whittington, 1965
Carinocranium Dean, 1989
Edmundsonia Cooper 1953
Jiuxiella Zhou et al. 1977
Lehnertia Vaccari, et al, 2006
Malongullia Webby, Moors & McLean, 1970
Miaopopsis Lu et al. 1965, synonym = Sinampyxina
Miboshania Zhang 1979
Pytine Fortey, 1975
Salteria Thomson, 1864
? Tarimella W. T. Zhang 1979 (may be a shumardiid ptychopariid)
Typhlokorynetes Shaw, 1966

References

^ ^a ^b Fortey, R.A. (1975). The Ordovician Trilobites of Spitsbergen [II. Asaphidae, Nileidae, Raphiophoridae and Telephinidae of the Valhallfonna Formation]. Norsk Polarinstitutt Skrifter. Vol. 162. Oslo: Norsk Polarinstitutt.
^ J.M. Adrian (2014). "20. A synopsis of Ordovician trilobite distribution and diversity". In D.A.T. Harper; T. Servais (eds.). Early Palaeozoic Biogeography and Palaeogeography. Memoirs of the Geological Society of London. Vol. 38. Geological Society of London. p. 490. ISBN 978-1862393738.
^ 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.

[Fortey_1975-1] Fortey, R.A. (1975). The Ordovician Trilobites of Spitsbergen [II. Asaphidae, Nileidae, Raphiophoridae and Telephinidae of the Valhallfonna Formation]. Norsk Polarinstitutt Skrifter. Vol. 162. Oslo: Norsk Polarinstitutt.

[HarperServais-2] J.M. Adrian (2014). "20. A synopsis of Ordovician trilobite distribution and diversity". In D.A.T. Harper; T. Servais (eds.). Early Palaeozoic Biogeography and Palaeogeography. Memoirs of the Geological Society of London. Vol. 38. Geological Society of London. p. 490. ISBN 978-1862393738.

[ZWY-3] 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.

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