Gnawed Bones from the Crag and Forest Bed Deposits of East Anglia

TRANSACTIONS GNAWED BONES FROM THE CRAG AND FOREST BED DEPOSITS OF EAST ANGLIA A . J . SUTCLIFFE a n d H . D . COLLINGS

bones gnawed by cave frequenting animals sometimes occur in great abundance in cave deposits, both in the recent and fossil State (Sutcliffe, 1969, 1970 bibliography), the preservation of gnawed bones as fossils outside caves is sufficiently uncommon to merit attention. On any present day land-surface, however, in areas where wild mammals are abundant, bones of those which have died are commonly widely scattered and some of these generally show marks where they have been splintered or gnawed, especially by carnivores and rodents. It would be surprising, therefore, were gnawed bones never to be found in the fossil State outside caves.

ALTHOUGH

Two important series of deposits where remains of fossil mammals are found outside caves occur in East Anglia. These are the marine and, in some cases, beach Crag deposits (Upper Pliocene to Lower Pleistocene) of Suffolk (Spencer, 1971), with remains of marine mammals and derived remains of land mammals (sometimes secondarily derived from earlier deposits); and the estuarine and freshwater Cromer Forest Bed Series (Lower to Middle Pleistocene) of Norfolk. The purpose of this paper is to place on record three gnawed bones from these deposits.

1.

Gnawed antler f r a g m e n t (PLATE 1A). Sub-Coralline Crag (Upper Pliocene) of Suffolk. Preserved in the Ipswich Museum.

This fragment of tine of a deer antler has been gnawed diagonally across the tip. It is unlikely that any carnivore could have achieved this. The clean-cut grooves are suggestive of porcupine, teeth of which are already known from the Crag. Present day porcupines are renowned for gnawing bones.

Mr. H. E. P. Spencer, who has an unrivalled knowledge of the State of preservation of Crag fossils, is of the opinion that this specimen probably comes from the base of the Coralline Crag and points out that Sutton, Suffolk, is the only place where subCoralline Crag fossils have been found.

2.

Gnawed deer metatarsal from the Norwich Crag Shell Bed (Antian) of Easton Bavents, Suffolk (PLATE 2A). Preserved in the British Museum (Natural History), registered number M29361. Collected and presented by Mr. I. J. Cruikshank.

PLATE

1A

Fragment of deer antler f r o m the Pliocene sub-Coralline Crag, Sutton, Suffolk, showing gnawing bv a porcupine.

Pl.ATE lB

Recent bones, gnavved by porcupines. Left, from the Ngorongoro Crater, Tanzania; right, from Kajiado, Kenya.

Photos: British Museum (Nat. His

PLATE 2A (left) Proximal end of t h e metacarpal of a deer f r o m t h e N o r w i c h C r a g of Easton Bavents, Suffolk, gnawed probably by a carnivore.

PLATE 2B, C (above) Recent bones gnawed by carnivores (in this case juvenile hyaenas), f r o m Kenya and T a n z a n i a .

Photos: British Museum (Nat. Hist.)

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This metatarsal fragment has been gnawed in a manner typical of carnivores. The gnawing is present on opposite faces and the damage has been caused by tearing rather than by chiselling. The porcupine (in any case not recorded from the Norwich Crag) gnaws on one side of a bone only. The tooth marks are approximately at right angles to the main elongation of the bone, as would be generally expected to occur when any animal gnaws an elongated object.

It is not possible to distinguish with certainty bones gnawed by different carnivores, especially since an adult small carnivore may leave tooth marks similar to those caused by the milk teeth of a juvenile large carnivore. Some idea of the size of the animal concerned, however, can be obtained from the magnitude of the tooth marks. At present only two species of carnivore are known from Easton Bavents—leopard and fox. The marks on the specimen seem decidedly too massive for fox.

3.

Gnawed metatarsal (not illustrated) of a horse from the Forest Bed of Sidestrand, Norfolk. Preserved in the British Museum (Natural History), registered number M19246.

Collected by A. C. Savin.

This bone has been extensively gnawed around the distal end, in a manner suggestive of a large carnivore. Many carnivores are known from the Forest Bed Series, including lion and hyaena.

Acknowledgements The writers gratefully acknowledge the help of Mr. I. J. Cruikshank who presented the deer metacarpal to the British Museum (Natural History); and to Mr. H. E. P. Spencer, who drew their attention to the existence of the two other gnawed specimens and who provided much help and information.

References Spencer, H . E. P. (1971). A contribution to Suffolk. Part 5. T h e Early Pleistocene. mammals. Suffolk Nat. Hist. 15, 279-363.

Sutcliffe, A. J. (1969). Adaptations of spotted British Isles. Bull. Mam. Soc. Brit. Isles 31, (1970). Spotted Hyaena: Crusher, Collector of Bones. Nature 227, 1110-1113.

the geological history of Crag epochs and their hyaenas to living in the 10-14.

Gnawer, Digester and

A. J. Sutcliffe, British Museum (Natural History), Cromwell Road, London, S.W.7, and H. D. Collings, 23 Station Road, Southzvold.