Belongs within: Asaphida.
Contains: Niobinae.
The Asaphacea are a group of trilobites known from the Upper Cambrian to the Upper Ordovician (Harrington et al. 1959).
The Ceratopygidae are a family of trilobites that lived from the Middle Cambrian to the Lower Ordovician. Members of the family possessed rear-pointing spines on both the cephalon and the pygidium.
Horny-arsed trilobites
Published 28 February 2015
Just a short post for today. The Ceratopygidae are a family of trilobites known from the Late Cambrian and Early Ordovician. The name of the type genus, Ceratopyge, means ‘horned rump’, and one of the features that has classically defined the family is the presence of one or two pairs of spines on either side of the pygidium, the plate the makes up that hind end of a trilobite. These spines appear to be derived from lateral extensions of one of the anterior segments incorporated into the pygidium. However, there are also some genera without pygidial spines that share other features with the family (such as a narrow rim to the cheeks) and so have also been recognised as ceratopygids. Ceratopygids also possessed narrow spines extending back from the posterior corners of the head. The number of segments between head and pygidium varied between genera: early genera have nine segments, but some later genera have only six (Fortey & Chatterton 1988) (offhand, the drawing above looks to have one too many segments).
Otherwise, ceratopygids seem to have been fairly generalised trilobites. The eyes were present but not large, and there don’t appear to be any features suggesting they were swimmers. The features of the underside of the head are poorly known in ceratopygids overally, but where known, the hypostome (the plate on the underside of the head that would have sat in front of the mouth) is firmly attached to the anterior margin of the head. Trilobites with this arrangement are believed to have been scavengers or predators on small invertebrates (Fortey & Owens 1999). In some later genera, such as Ceratopyge, the glabella in the midline of the cephalon expanded forward, with a corresponding reduction in the width of the anterior margin. As the glabella would have contained the trilobite’s stomach, its enlargement may indicate that these later ceratopygids were taking larger prey.
Systematics of Asaphoidea
Characters (from Harrington et al. 1959, as Asaphacea): Thoracic segments usually 8 (occasionally 7). Eyes commonly more or less conical, short or moderate in length; eyes ridges present in a few genera, faint or scarcely discernible. Pygidium rounded or with one or two terminal spines.
Asaphoidea [Asaphacea, Ceratopygacea]
| i. s.: MegalaspidesS80
| NotopeltisS80
| MegalaspidellaS80
| Charchaqia noriniSS84, CT83
| LycophronF90
| HedinaspisF90
| |--H. regalisCT83
| `--H. shengiCT83
|--AsaphidaeS80
| | i. s.: AsaphusF71
| | | i. s.: A. expansusSG93
| | | A. kowalewskiiFO99
| | |--A. (*Basilicus) tyrannusR27
| | `--A. (Megalaspis Angelin 1854)F71, W77
| | |--‘Megalaspis’ belemnurus White 1874W77
| | |--‘Megalaspis’ extenuatusH04
| | |--A. (M.) goniocercusW77
| | `--A. (M.) howchini Etheridge 1894F71
| | OgygitesR27
| | |--O. birmanicusR27
| | |--O. collingwoodensis Reed 1927R27
| | |--‘Basilicus’ kegelensisR27
| | |--O. kuckersianus [=Asaphus (Basilicus) kuckersianus]R27
| | |--‘Basilicus’ lawrowiR27
| | `--O. yunnanensisR27
| | OgygyinusFO99
| | |--O. armoricanusFO99
| | `--‘Ogygia’ corndensisR27
| | PseudoasaphusJB12
| | PseudobasilicusJB12
| | Griphasaphus griphus Öpik 1967RC93
| | Ectenaspis beckeriRC93
| | IsotelusF90
| | |--I. gigasP98
| | `--I. parvirugosusFO99
| `--NiobinaeS80
`--CeratopygidaeRC93
| i. s.: Pseudohysterolenus Harrington & Leanza 1957S80
| Onychopyge Harrington 1938SS84
| Bicornipyge Lisogor 1961SS84
| Ceratopyge forficulaRC93
|--IwayaspidinaeS80
| |--Cermatops Shergold 1980S80
| | `--C. vieta Shergold 1980S80
| `--Iwayaspis Kobayashi 1962S80
| |--I. asaphoides Kobayashi 1962S80
| |--I. caelata Lazarenko in Datsenko et al. 1968S80
| |--I. curta Lazarenko in Datsenko et al. 1968S80
| `--I. longa Lazarenko in Datsenko et al. 1968S80
|--ProceratopyginaeS80
| |--Aplotaspis Henderson 1976S80
| |--ProceratopygeS80
| | |--P. chuhsiensis Lu 1956S80
| | |--P. (Sinoproceratopyge) constrictaCT83
| | |--P. lataS80
| | `--P. polita Whitehouse 1939S80
| `--Haniwoides Kobayashi 1935S80
| |--*H. longa Kobayashi 1935S80
| |--H. concava Kobayashi 1935S80
| |--H. longissima Kobayashi 1962S80
| |--H. puteolata Kobayashi 1962S80
| |--H. tenuis Kobayashi 1962S80
| `--H. varia Shergold 1980S80
`--Macropyginae [Macropygidae]RC93
|--Aksapyge Lisogor 1977SS84
|--Promacropyge Lu 1965SS84
| `--P. carinataCT83
`--Macropyge Stubblefield 1927 [incl. Gladiatoria Hupé 1955, Lichapyge Callaway 1877]SS84
|--*M. chermi Stubblefield 1927SS84
|--M. ambolti (Troedsson 1937) [=Haniwa ambolti]SS84
|--M. brevicaudata Wolfart 1970SS84
|--M. elegansis Fedjanina in Sinyakov & Fedjanina 1962SS84
|--M. gladiator Ross 1951 [=*Gladiatoria gladiator]SS84
|--M. improcera Lisogor 1977SS84
|--M. kozhuchensis (Petrunina 1973) [=Niobella kozhuchensis]SS84
|--‘Lichapyge’ problematicaR27
|--M. sica Sdzuy 1955SS84
`--M. taurina Dean in Özgül, Metin & Dean 1972SS84
Nomina nuda: Macropyge composita Petrunina 1966SS84
Macropyge kasica Petrunina 1966SS84
Macropyge lanceolata Petrunina 1966SS84
Macropyge poletaevae Petrunina 1966SS84
Macropyge prisca Petrunina 1966SS84
Macropyge tabularis Petrunina 1966SS84
*Type species of generic name indicated
References
[CT83] Chen J.-Y. & C. Teichert. 1983. Cambrian Cephalopoda of China. Palaeontographica Abteilung A: Paläozoologie—Stratigraphie 181 (1–3): 1–102.
[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.
[F90] Fortey, R. A. 1990. Ontogeny, hypostome attachment and trilobite classification. Palaeontology 33 (3): 529–576.
Fortey, R. A., & B. D. E. Chatterton. 1988. Classification of the trilobite suborder Asaphina. Palaeontology 31 (1): 165–222.
[FO99] Fortey, R. A., & R. M. Owens. 1999. Feeding habits in trilobites. Palaeontology 42 (3): 429–465.
[H04] Haeckel, E. 1899–1904. Kunstformen der Natur. Bibliographisches Institut: Leipzig und Wien.
Harrington, H. J., G. Henningsmoen et al. 1959. Systematic descriptions. In: Treatise on Invertebrate Paleontology pt O. Arthropoda 1 pp. O170–O540. Geological Society of America and University of Kansas Press.
[JB12] Johnson, M. E., & B. G. Baarli. 2012. Development of intertidal biotas through Phanerozoic time. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 63–128. Springer.
[P98] Prothero, D. R. 1998. Bringing Fossils to Life: An introduction to paleobiology. WCB McGraw-Hill: Boston.
[R27] Reed, F. R. C. 1927. New trilobites from the Ordovician beds of New Zealand. Transactions and Proceedings of the New Zealand Institute 57: 310–314.
[RC93] Romano, M., W. T. Chang, W. T. Dean, G. D. Edgecombe, R. A. Fortey, D. J. Holloway, P. D. Lane, A. W. Owen, R. M. Owens, A. R. Palmer, A. W. A. Rushton, J. H. Shergold, D. J. Siveter & M. A. Whyte. 1993. Arthropoda (Trilobita). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 279–296. Chapman & Hall: London.
[S80] Shergold, J. H. 1980. Late Cambrian trilobites from the Chatsworth Limestone, western Queensland. Bureau of Mineral Resources, Geology and Geophysics—Bulletin 186: 1–111.
[SS84] Shergold, J. H., & K. Sdzuy. 1984. Cambrian and early Tremadocian trilobites from Sultan Dağ, central Turkey. Senckenbergiana Lethaea 65 (1–3): 51–135.
[SG93] Simms, M. J., A. S. Gale, P. Gilliland, E. P. F. Rose & G. D. Sevastopulo. 1993. Echinodermata. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 491–528. Chapman & Hall: London.
[W77] White, C. A. 1877. Report upon the invertebrate fossils collected in portions of Nevada, Utah, Colorado, New Mexico, and Arizona, by parties of the expeditions of 1871, 1872, 1873, and 1874. U.S. Geographical Surveys West of the One Hundredth Meridian 4 (1): 1–219, pls 1–21.