New Mammalian Fossils from Red Crag

NEW MAMMALIAN FOSSILS FROM RED CRAG HAROLD E . P .

SPENCER

ONE of the fascinations of the study of the mammalian fossils of the Crags is that something new may come to light at any time.

DĂźring his recent visit in July, Dr. Miklos Kretzoi, senior scientist at the Hungarian State Institute, Budapest, and a specialist on Neozoic mammals, determined some hitherto unrecognised teeth during a two day visit to Ipswich, while a guest of the British Council.

An old worn tooth discovered during the researches of J. Reid Moir in the Crag sands at Bramford during the 1920s and thought to have belonged to a beaver, proved to be a left lower fourth premolar of Histrix. It is therefore the first record of Porcupine from the Pleistocene Red Crag. Remains of deer and whale of Villafranchian age were also discovered in the same deposit. (See " The Prehistoric Deer of the East Anglian Crag Deposits " Trans. Suffolk Nats. 12 : 262-266), 1963.

A subsequent visit to the British Museum (Natural History) resulted in the discovery of a tooth which also came from an aged animal, and had it been found at the same site could have been considered as probably from the same beast. It is recorded as Castor fiber, Felixstowe, M.9595, but with a pencilled note— " can this be Histrix ? ". It was purchased from the Warburton collection in 1907.

The difficulty in determining teeth of the large rodents is that the pattern formed by the enamel folds varies as the teeth are worn down and, in the absence of comparative series of teeth in different stages of wear, precise identification is difficult by a nonspecialist.

A heavily mineralised tooth, much rounded by water action, which was found by R. A. D. Markham in the Red Crag at Alderton and not identified, proved to be a left lower third premolar of Prolagus. (Prolagus is related to the ancestors of the Hares.)

This is believed to be the first record of the genus for Britain and was probably derived from a former Miocene deposit destroyed by the Crag Sea. The tooth is only seven millimetres long.

With the Bramford " Beaver " tooth referred to Histrix, it is fortunate that a left lower fourth premolar of Castor sp. Cf. fiber, was discovered in the Red Crag at Beggar's Hollow, Clapgate Lane, Ipswich, by D. T. Adlem. Thus the Beaver remains on the list of Crag fauna and is the first confirmed record for the Ipswich district.

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Dr. Kretzoi also noticed amongst the large series of Mastodon teeth in the Museum, incomplete molars of the Miocene Mastodon Tetrabelodon (TrĂźophodon) angustidens, Cuvier, which had been confused with the closely similar teeth of T. (Tetralophodon) longirostris, Kaup, which is a lower Pliocene species. T h e significance of this will be considered later. In his " British Fossil Mammals and Birds " Sir Richard Owen mentions teeth of " Mastodon angustidens " (page 271) but his figures are of M. (Anancus) arvernensis, Croizet and Joubert, of the middle and Upper Pliocene. This species appears to have survived into the Early Pleistocene in Italy and it is uncertain if it did not do so here also. T h e skeleton of one is recorded below the Norwich Crag at Horstead, Norfolk. No bones, only teeth have been discovered in the Crag itself or its basement bed.

Although the teeth of the Mastodons attracted the attention of the older authorities on Crag mammalian fossils (the teeth being the most coveted fossils by collectors who are recorded as having paid from six to twenty pounds for the best preserved specimens) they do not appear to have considered the implications.

The teeth were found below the Coralline as well as below the Red Crag, but until 1948 all the Crags were generally believed to be of Pliocene age, a fact which undoubtedly strongly biased their views. The important fact is that remains of land animals of various ages occurred together below a marine deposit which implies the submergence of a continent and the consequent destruction of lake and river deposits which contained remains of drowned beasts.

The presence of fossils representing the principle formations from the Eocene upwards may also be regarded as representative of a series of similar events, i.e., alternating continental and marine epochs. Although some terrestrial mammals are represented—Coryphodon, Hyracotherium, and Lophiodon— the greater number of fossils from the Eocene are marine. T h e Miocene, which was believed not to be represented in British geological deposits, has now a good deal of material evidence from the Crag Basement Bed showing that former terrestrial and marine deposits existed. This consists of the mammalian fossils already mentioned and the " Boxstone " molluscan fauna, cetacean teeth and those of the giant shark, Carcharodon megalodon. T h e Pliocene continental phase is represented, in addition to the Mastodont species, by the axis deer, A. pardinensis, Croizet and Joubert, Cervus suttonensis, Hipparion, etc., and the marine by the remnants of the Coralline Crag. Remains of horses and elephants in the Red Crag Basement point to an earlier phase of the Pleistocene destroyed partly by ice of an early glaciation, of which

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Jurassic and Cretaceous erratics from Yorkshire and striated flints are evidence, and mostly by the incursion of the Red Crag Sea which rose to at least 150 feet above the present level.