Saturday, March 25, 2017

[Paleontology • 2017] Cascolus ravitis • A New Crustacean from the Herefordshire (Silurian) Lagerstätte, UK , and Its Significance in Malacostracan Evolution


Cascolus ravitis 
Siveter, Briggs, Siveter, Sutton & Legg, 2017  


Abstract

Cascolus ravitis gen. et sp. nov. is a three-dimensionally preserved fossil crustacean with soft parts from the Herefordshire (Silurian) Lagerstätte, UK. It is characterized by a head with a head shield and five limb pairs, and a thorax (pereon) with nine appendage-bearing segments followed by an apodous abdomen (pleon). All the appendages except the first are biramous and have a gnathobase. The post-mandibular appendages are similar one to another, and bear petal-shaped epipods that probably functioned as a part of the respiratory–circulatory system. Cladistic analysis resolves the new taxon as a stem-group leptostracan (Malacostraca). This well-preserved arthropod provides novel insights into the evolution of appendage morphology, tagmosis and the possible respiratory–circulatory physiology of a basal malacostracan.

An international team of scientists led by the University of Leicester has discovered a new 430 million-year-old fossil and has named it in honour of Sir David Attenborough - who grew up on the University campus.  

Systematic palaeontology

Phylum Arthropoda
Subphylum Crustacea

Class Malacostraca
Subclass Phyllocarida

Order Leptostraca

Genus Cascolus gen. nov.

Type species: Cascolus ravitis sp. nov.

Etymology: The new crustacean is named in honour of the naturalist and broadcaster Sir David Attenborough, who grew up on University College Leicester campus, in celebration of his 90th birthday. Latin castrum stronghold’ and colus dwelling in’; alluding to the Middle/Old English source for the surname ‘Attenborough, derived from attenat the’ and burgh a fortified place’. Latin Ratae, the Roman name for Leicester, vita life’ and commeatis ‘a messenger’.


  Diagnosis of genus (monotypic) and species: An elongate body comprising a head with a head shield, pedunculate eyes and five limb pairs; and a trunk consisting of a thorax (pereon) with nine limb-bearing segments and an apodous abdomen (pleon). The first appendage is uniramous and has three slender flagella longer than the body. All other appendages are biramous and have a gnathobase. The post-mandibular appendages are similar to one another, except that the fourth head appendage bears a single petal-shaped epipod, and the fifth head appendage and each trunk appendage bear two petal-shaped epipods.

  Material: Only known from the holotype OUMNH C.29698 (figure 1v), a specimen with soft parts reconstructed in three dimensions (figure 1a–u).

  Locality and horizon: Herefordshire, England, UK; Wenlock Series, Silurian.


David J. Siveter, Derek E. G. Briggs, Derek J. Siveter, Mark D. Sutton and David Legg. 2017. A New Crustacean from the Herefordshire (Silurian) Lagerstätte, UK, and Its Significance in Malacostracan Evolution. Proceedings of the Royal Society B.  DOI: 10.1098/rspb.2017.0279 

 430 million-year-old fossil named in honor of Sir David Attenborough
 http://phy.so/409322871   @physorg_com

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