26 D3. Topics in General Paleontology and Ichnology

Tuesday, 10 March 2020
1:30 PM - 5:30 PM
Meeting Room 201C

A DEEP-BODIED ICHTHYOSAUR (REPTILIA: ICHTHYOSAURIA) FROM THE UPPER JURASSIC KIMMERIDGE CLAY FORMATION OF DORSET, UK: IMPLICATIONS OF RIB CAGE ARCHITECTURE FOR ICHTHYOSAUR PALAEOECOLOGY

Paper number: 26-4
Program: Technical Sessions
Time: 2:15 PM – 2:35 PM

Authors

Abstract

A new ichthyosaur specimen (MJML K1885) from the Late Jurassic (Kimmeridgian) Kimmeridge Clay Formation of Dorset, United Kingdom is described. The specimen, expertly prepared on a slab of laminated coccolith limestone, comprises a near complete skull, in articulation with the anterior vertebral column and associated thoracic ribs, complete pectoral girdle, fully exposed left forelimb, and some elements of the right forelimb.]

Aspects of the dentition, skull roof bones and the forelimb configuration distinguishes the new specimen from previously described Late Jurassic ichthyosaurs, and consequently it is referred to a new genus and species. A cladistics analysis reveals a close relationship with Nannopterygius with which the new taxon may form a distinct family as a sister clade to Ophthalmosauridae. A unique feature of MJML K1885 is its extremely deep anterior rib cage, suggesting perhaps a deep-diving habitat.

The new specimen adds to the diversity of Kimmeridge Clay Formation ichthyosaurs, and emphasises the important contribution of amateur collectors in palaeontology.

Geological Society of America Abstracts with Programs. Vol. 52, No. 1

doi: 10.1130/abs/2020SC-343307

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