Aegirocassisinae

Aegirocassisines
Temporal range: Lower Ordovician, 485–475 Ma[1]
Restoration of Aegirocassis benmoulai
Fossil endites of Pseudoangustidontus duplospineus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Order: †Radiodonta
Family: †Hurdiidae
Subfamily: †Aegirocassisinae
Potin, Gueriau & Daley, 2023
Genera

Aegirocassisinae is a subfamily of radiodonts (marine stem-arthropods) from the lower Paleozoic era. It belongs to the larger hurdiidae (peytoiid) family, which were the most diverse and long lasting radiodonts. The members of this subfamily are restricted to the Lower Ordovician-aged Fezouata Formation of Morocco. Currently only two genera are included: Aegirocassis and Pseudoangustidontus. These two genera possess large Baleen-like auxiliary spines on their frontal appendages, which suggests a suspension feeding lifestyle for the group. These radiodonts are some of the few known from sediments beyond the Cambrian period. This subfamily shows that following the Great Ordovician Biodiversification Event, which saw a rise in the plankton population in the worlds oceans, suspension feeding became more common in radiodonts then other feeding styles. It also seems that due to the evolution of new predators, like large nautiloid cephalopods, and other arthropod groups like the eurypterids, the radiodonts evolved suspension feeding lifestyles in order to minimize competition for food.[2][1][3][4]

  1. ^ a b Potin, G. J.-M.; Gueriau, P.; Daley, A. C. (2023). "Radiodont frontal appendages from the Fezouata Biota (Morocco) reveal high diversity and ecological adaptations to suspension-feeding during the Early Ordovician". Frontiers in Ecology and Evolution. 11. 1214109. doi:10.3389/fevo.2023.1214109.
  2. ^ Van Roy, Peter; Briggs, Derek E. G. (2011). "A giant Ordovician anomalocaridid". Nature. 473 (7348): 510–513. Bibcode:2011Natur.473..510V. doi:10.1038/nature09920. ISSN 1476-4687. PMID 21614078. S2CID 205224390.
  3. ^ Gabriele Kühl; Derek E. G. Briggs & Jes Rust (2009). "A great-appendage arthropod with a radial mouth from the Lower Devonian Hunsrück Slate, Germany". Science. 323 (5915): 771–773. Bibcode:2009Sci...323..771K. doi:10.1126/science.1166586. PMID 19197061. S2CID 47555807.
  4. ^ Servais, T.; Owen, A. W.; Harper, D. A. T.; Kröger, B. R.; Munnecke, A. (2010). "The Great Ordovician Biodiversification Event (GOBE): the palaeoecological dimension". Palaeogeography, Palaeoclimatology, Palaeoecology. 294 (3–4): 99–119. Bibcode:2010PPP...294...99S. doi:10.1016/j.palaeo.2010.05.031.