Morphology and anatomy of the Late Jurassic Mayrocaris bucculata (Eucrustacea?, Thylacocephala) with comments on the tagmosis of Thylacocephala

Laville, Thomas; Haug, Carolin; Haug, Joachim T.; Forel, Marie-Beatrice und Charbonnier, Sylvain (2021): Morphology and anatomy of the Late Jurassic Mayrocaris bucculata (Eucrustacea?, Thylacocephala) with comments on the tagmosis of Thylacocephala. In: Journal of Systematic Palaeontology, Bd. 19, Nr. 4: S. 289-320

Abstract

Known from at least the Silurian (c. 435 Ma) up to the Late Cretaceous (c. 85 Ma), thylacocephalans are among the most intriguing fossil euarthropods. They are characterized by a prominent shield enveloping most of the body, hypertrophied compound eyes, three pairs of large, raptorial appendages and a trunk with 8-22 stout segments bearing appendages. Despite this knowledge of their anatomy, the phylogenetic affinities of Thylacocephala are controversial due to a lack of knowledge on their body organization and tagmosis. This study focuses on Mayrocaris bucculata Polz, 1994 from the Solnhofen Lagerstatte, Germany (c. 150 Ma, early Tithonian, Jurassic). We document new specimens of Mayrocaris bucculata from the Solnhofener Plattenkalke sensu lato and provide new descriptions for previously reported specimens. We demonstrate that the raptorial appendages of Thylacocephala are most probably maxillulae, maxillae and maxillipeds. Additionally, we report new details on the posterior trunk appendages, including the description of a paddle-like proximal part and of a rod-like distal part, but also of a specialized terminal trunk appendage. These new findings, in addition to the reinterpretation of a cephalic appendage of Clausocaris lithographica as a possible mandible, are essential for a better understanding of the body organization in thylacocephalans and their phylogenetic affinities within Eucrustacea.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Biologie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften; Biologie
• ISSN: 1477-2019
• Sprache: Englisch