Archive for July 10th, 2015

Wooster’s Fossil of the Week: A small lobster from the Lower Cretaceous of North Yorkshire, England

July 10th, 2015

Meyeria ornata fullMae Kemsley (’16) found this little beauty during her Independent Study fieldwork last month on the Speeton Cliffs of North Yorkshire. It is Meyeria ornata (Phillips, 1829), a decapod of the lobster variety, from the Speeton Clay. It is relatively common in Bed C4, so much so that it is referred to as “the shrimp bed”. Mae is the only one of our team of four who found one, though, so it is special to us. The above is a lateral view, with the head to the left and abdomen on the top of this small concretion.
Dorsal Meyeria ornataHere is a dorsal view looking down on the abdominal segments.
Screen Shot 2015-07-01 at 9.14.03 PMSimpson and Middleton (1985, fig. 1b) have this excellent diagram of Meyeria ornata in life position. The scale bar is one centimeter. “Details of pleopods, third maxillipeds and first antennae of M. ornata unknown. Dashed line represents length of extended abdomen. Symbols: a branchiocardiac groove; c postcervical groove; e cervical groove; m3 third maxilliped; p pereiopod; pi pleopod; t telson; u uropods; x ‘x’ area; r rostrum; al first antennae; a2 second antennae; ar antennal ridge; sr suborbital ridge; 1,2,3. branchial ridges.”

According to Simpson and Middleton (1985), Meyeria ornata actively crawled about on the muddy substrate like modern lobsters. They did not have true chelae (large claws), so they were likely scavengers in the top layers of the sediment rather than predators.

3 Mae working 060915Mae at work.

References:

Charbonnier, S., Audo, D., Barriel, V., Garassino, A., Schweigert, G. and Simpson, M. 2015. Phylogeny of fossil and extant glypheid and litogastrid lobsters (Crustacea, Decapoda) as revealed by morphological characters. Cladistics 31: 231-249.

M’Coy F. 1849. On the classification of some British fossil Crustacea with notices of new forms in the University Collection at Cambridge. Annals and Magazine of Natural History, series 2, 4, 161-179.

Phillips, J. 1829. Illustrations of the geology of Yorkshire, Part 1. The Yorkshire coast: John Murray, London, 184 p.

Simpson, M.I. and Middleton, R. 1985. Gross morphology and the mode of life of two species of lobster from the Lower Cretaceous of England: Meyeria ornata (Phillips) and Meyerella magna (M’Coy). Transactions of the Royal Society of Edinburgh: Earth Sciences 76: 203-215.