Thylacocephala Pinna, Arduini, Pesarini & Teruzzi, 1982

Laville, Thomas, Forel, Marie-Béatrice & Charbonnier, Sylvain, 2023, Re-appraisal of thylacocephalans (Euarthropoda, Thylacocephala) from the Jurassic La Voulte-sur-Rhône Lagerstätte, European Journal of Taxonomy 898 (1), pp. 1-61 : 10

Class Thylacocephala Pinna, Arduini, Pesarini & Teruzzi, 1982

Original diagnosis ( Schram 1990)

These are arthropods with a small to large bilobed carapace enclosing the entire body. Compound eyes very well developed as either large, sessile bodies situated in optic notches or as organs that virtually cover the surface of a protrudent, sac-like cephalon. Body appendages are of two types: anteriorly 3 pairs of subchelate, raptorial limbs, and posteriorly a set of from 8 to 16 pairs of apparently paddle-like limbs. Eight sets of well-developed gills are associated with the subchelate limbs. The posterior trunk is marked with pronounced pleurites, probably developed internally as an endrophragmal skeleton, associated with the posterior limbs.

Remarks

We decide not to follow the attempt of classification proposed by Schram (2014) as it has been shown to present many issues (e.g., polyphyly of Concavicarida Briggs & Rolfe, 1983 and Conchyliocarida Secrétan, 1983, problems with the definition of autapomorphies for many taxa; see Hegna et al. 2014 and Laville et al. 2021a, 2021b for detailed explanations).