Biology:Hollardops

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Short description: Extinct genus of trilobites


Hollardops
Temporal range: Emsian–Eifelian
Hollardops mesocristata, Early Devonian, TazoulaOt Formation, Jbel OufatEne & Jbel Issoumour, MaOder Region, Morocco - Houston Museum of Natural Science - DSC01602.JPG
Hollardops sp.
Houston Museum of Natural Science - DSC01602
Scientific classification
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Phylum:
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Subfamily:
Asteropyginae
Genus:
Hollardops

Morzadec, 1997
Species
  • Asteropyge mesocristata Le Maître, 1952
  • Chatterton et al., 2006 Morzadec, 1983
  • Lieberman & Kloc, 1997 H. kyriarchos
  • Philipsmithiana burtandmimiae Van Viersen & Kloc, 2022
  • H. angustifrons Lieberman & Kloc, 1997
  • Van Viersen & Kloc, 2022 H. luscus
  • H. boudibensis Van Viersen & Kloc, 2022
  • H. aithassainorum Van Viersen & Kloc, 2022
  • Morzadec, 2001 Van Viersen & Kloc, 2022
  • Greenops struvei Rhenops circumapodemus
  • Morzadec, 1969 Rhenops babini
  • Smeenk, 1983 H. multatuli
  • H. klugi Philipsmithiana hyfinkeli

Hollardops is a genus of trilobite in the order Phacopida that lived during the Devonian. Their fossils are found in the upper Emsian of western Europe (France, Spain) and in the lower Emsian to lowermost Eifelian of North Africa (Morocco, Algeria). The type species, Asteropyge mesocristata, was described from Algeria by Le Maître in 1952. The genus Hollardops was erected by Morzadec in 1997.[1] In the same year, Lieberman & Kloc[2] erected Modellops and Philipsmithiana but those genera are regarded as subjective synonyms of Hollardops. The 10-segmented thoracic condition of Hollardops is a rare feature among acastid trilobites that almost always have 11 thorax segments. Van Viersen & Kloc (2022)[3] revisited Hollardops and described a number of new species from the Devonian of Morocco. They also regarded Pennarbedops Bignon & Crônier, 2013 as a synonym of Hollardops. Van Viersen & Kloc construed Hollardops as a scavenger or predator with well-developed eyes, that used its shovel-like cephalon to plough the top layers of the sediment in search of food. Hollardops had small pits horizontally along the fringe of the exoskeleton; these are believed to have housed setae that allowed the trilobite to closely monitor its surroundings.

Description

Hollardops sp.
Houston Museum of Nat. Sci. - DSC01611
Both specimen are from Tazoulait Formation at
Jbel (Jebel) Oufatène [ ⚑ ] 30°50′15″N 4°54′07″W / 30.8374368°N 4.9018067°W / 30.8374368; -4.9018067 (Jbel Oufatène)[4]
and Issimour [ ⚑ ] 30°58′01″N 5°02′14″W / 30.9669834°N 5.0373266°W / 30.9669834; -5.0373266 (Jbel Issimour)[5]
SE of Alnif, western of Oued Alnif, Ma'ider region, Morocco

Hollardops have schizochroal eyes and a glabella that is slightly raised on the surface of the cephalon. Genal spines extend from the cephalon and extend to approximately the 6th thoracic segment.

Hollardops has 10 thoracic segments and also has 5 pairs of pleural lappets or spines projecting from the pygidium.

Length ranges from approximately 3 to 9 cm.

References

Wikidata ☰ Q55639894 entry