The Xenodiscidae are the earliest of the Ceratitida and comprise Middle and Upper Permian genera characterized by compressed, discoidal, evolute shells with rounded to acute venters and commonly with lateral ribs. Sutures are goniatitic to weakly ceratitic.[1]
| Xenodiscidae Temporal range:
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| Xenodiscus besairiei on display at the Museo Civico di Storia Naturale di Milano | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | †Ammonoidea |
| Order: | †Ceratitida |
| Superfamily: | †Xenodiscoidea |
| Family: | †Xenodiscidae Frech, 1902 |
| Genera | |
The Xenodiscidae, which are part of the superfamily Xenodiscoidea, are derived from the Daraelitidae, a family in the Prolecanitida (ibid). In turn, the Xenodiscidae provided the root stock for the subsequent expansion and diversification of the Ceratitida in the Triassic.
Notes edit
- ^ Arkell et al, 1957
References edit
- Arkell et al., 1957; Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology, Part-L, Ammonoidea; Geological Soc. of America, reprinted 1990.
- The Paleobiology Database July 2009
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