A Lower Cretaceous Lobster from the Speeton Clay Formation

Lateral view of Hoploparia dentata. 

Again in the series of revisited draft postings, here is a brief account of the discovery of a near complete Lower Cretaceous Lobster fossil from Speeton, Yorkshire. Since this discovery I have actually gone on to form a bit of a collection of fossil crustaceans, predominantly from phosphate nodules including a Glyphea fossil from the Jurassic Waterloo Mudstone Formation. 

From March 2022: Last week I was lucky enough to return to the Speeton Clay Formation, exposed along a section of coastline south of Reighton Gap towards Flamborough Head on the Yorkshire coast. Its a fantastic site, not only for it's quality of mud, such maligned by fossil hunters, but some exceptionally well preserved Lower Cretaceous fossils, ranging in size from the 'Speeton Plesiosaur' [1] to the plentiful foraminifera [2].

Speeton beach (south of Reighton Gap) looking towards Flamborough Head.

I've only ever been to these exposures once before, where I collected a range of fossils, however, the site is relatively popular and I last visited in summer, so finds were relatively scarce. The most common finds are belemnites and this lead me to reconstruct their soft-body parts (-click here-), however, during this visit, my finds were not only plentiful but far more diverse (see below).

A selection of fossils from the Speeton Clay Formation (lacking scale) in situ: top left: a belemnite (Hibolites cf. torpedinus); top right: a heavily pyritised piece of wood; middle left: the front part of the cephalothorax of a lobster (Hoploparia dentata); middle right: fish vertebrae; bottom right: a 'Speeton shrimp', a lobster (Meyeria ornata) in a phosphate nodule showing the abdominal segments and cephalothorax and bottom left: an ammonite (Parasteria?).

The absolute highlight of the visit was the discovery of a phosphate nodule containing an uncommon lobster fossil, a find that I was, before the find, completely unaware of being present in the Speeton Clay Formation. I was, however, aware that the clays contained a couple of horizons containing phosphate nodules encasing 'Speeton shrimps', a small lobster like crustacean that lacks the 'claw' on the first leg. As a result, from the initial discovery of the find, through to the extraction and rest of the day, I thought that this was the famed 'Speeton shrimp', not realising that they are 1/3 the size of my find.

The process of extracting the lobster from the clay.

The lobster in situ.

Below is a photograph and reconstruction of the fossil. Subsequently, the fossil underwent some preparation work to remove some of the surrounding phosphate nodule matrix, revealing more of the specimen, especially around the claw. 

As seen in the prior photographs, a wide variety of other fossils were found, including some wonderful Meyaria ornata 'Speeton shrimps', however, one of the best samples I took was a bag of the clay itself. This allowed me to sieve out some of the plentiful foraminifera from the clay which were fantastically diverse. While Lenticulina (5-7) were particularly common, my favourite had to be Frondicularia, a particularly spectacular foraminifera. 

Larger foraminifera of the Speeton Clay Formation: 1: Frondicularia, 2: Frondicularia cf. concinna, 3: Citharina, 4: Nodosaria, 5-7: Lenticulina and 8: Lenticulina cf. guttata (scale bar: 1mm).

This chance find was certainly one of the highlight specimens of my fossil hunting year, the majority of which I don't share, however, I may start and post more of my unusual or interesting finds. 

[1] Speeton Plesiosaur; The Plesiosaur Site. Accessed at https://plesiosaur.com/page.php?pageID=10 on the 16/03/22.

[2] Fletcher BN, 1966. Lower Cretaceous foraminifera from the Speeton clay of Yorkshire. Doctoral thesis: Department of Geology, The University of Hull. Accessed at https://hydra.hull.ac.uk/resources/hull:13394 on the 16/03/22.