The Contemporary Mammalian Fossils of the Crags

TRANSACTIONS THE

CONTEMPORARY MAMMALIAN THE CRAGS*

FOSSILS

OF

HAROLD E . P . SPENCER, F.G.S.

The Pleistocene epoch is the most recent geological formation, and the deposits are possibly the most wide-spread, the most accessible and of which few rocks have given rise to so much controversial theory. It has only recently been proved to have endured for a longer period than most geologists have been prepared to accept and there is a possibility that evidence may yet show a longer duration than the two million years so far indicated. This period is one, more than any other, of greatest interest to mankind as it is the one during which Man-Ape progressed to Ape-Man and eventually MAN. About a Century ago, during the extensive exploitation of the Red Crag of Suffolk for " coprolites ", the raw material used in the infant artificial fertiliser industry, large numbers of fossil shells and a lesser number of mammalian remains were collected (as are postage stamps today), and large collections were formed, some of which eventually sold for sums up to -ÂŁ200. Occasionally as much as ÂŁ6 was paid for individual specimens such as a well preserved Mastodon molar. It is regrettable many of these collections were split up and some scientifically important specimens sold out of the country.

The human mandible which was discovered in the Red Crag at Foxhall, near Ipswich, about 1855 was possibly the most important fossil ever found in this country, or even in the world, but because it was a Crag fossil it was not acceptable to the scientific world as the deposit was then erroneously held to be of the Pliocene age.

However, the condition of the bone as described closely resembles that of the series of fossil mammalian remains now recognised as the true Crag fauna, to which in all probability the Foxhall jaw belongs. This controversial fossil was secured by a Dr. Collyer who took it to the United States where it appears to have been lost. Dr. L. Eisley, in the Kansas Science Journal (1943), has commented on the triple menta foramina which are a very primitive feature. *

Originally read to t h e A n n u a l M e e t i n g of T h e British Association ior the A d v a n c e m e n t of Science at N o r w i c h on S e p t e m b e r 6th, 1961.

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In the first Memoir of the Geological Survey, " The Geology of the Country around Ipswich, Hadleigh and Felixstowe" William Whitaker (1885) states there were two classes of fossil bones in the Red Crag, one relatively soft and frangible (a), the other " very solid and readily took a high polish " (b). It is greatly to be regretted that the former had small appeal for collectors and few have been preserved, but the second class which have a pleasing glossy appearance were greatly sought after. Until recent years only the Reverend Professor Henslow, (a former President of the Ipswich Museum) seems to have recognised the more or less unmineralised bones " as the true Crag fossils ", (Report of the British Association for 1847 (1848) p.64).

It is Whitaker's first class (a) which is to be regarded as of greater scientific importance affording evidence of the true age of the Red Crag, but outstanding specimens which were luckily preserved were explained away without any effort having been made to discover the truth. Sir E. Ray Lankester, writing on the elephant teeth from FALKENHAM, stated they could not be from the Crag but must have come from sands overlying the Crag. At this particular site the only deposits are London Clay and Red Crag, the Upper part being decalcified which is usual.. By their unrolled condition these teeth suggest they were protected by the bone of the mandible which had survived in a much decomposed State, but was much too decayed for preservation when excavated. Possibly the erroneous attribution of the Red Crag to the Pliocene epoch led to the unwitting acceptance of well preserved teeth of the Mastodon, Anancus arvernensis (A. falconeri, Osborn) as contemporary fossils.

Their true place is the Continental phase preceding the formation of the Pliocene Coralline Crag, (now the only British Pliocene formation since the Plio-Pleistocene boundary was redrawn in 1948 on the occasion of the London meeting of the International Geological Congress). The evidence of the mammalian fauna now presented proves the correctness of this revision.

T h e harder and generally glossy fossils are, with few exceptions, all derived from older geological formations which were destroyed as the Red Crag Sea rose to at least 150 feet above present sea level, or by the glaciation which appears to have preceded its incursion over north east Essex and south east Suffolk at least as far inland as Sudbury. Erratic fossils and rocks from Jurassic, Cretaceous, Eocene, Miocene and Pliocene ages occur together in the sub-Crag Basement Bed ; Carboniferous erratics (coal and clay-ironstone) are common in the Norwich Crag at Holton, Nr. Haiesworth. These became incorporated in a basal conglomeration in the same way as material from present-day eroded cliffs become mixed up with lost coins and flotsam and jetsam in geological deposits now being formed. This series of fossils is very valuable evidence proving the former existence of deposits which have vanished.

CRAG MAMMAI.S

335

By far the largest series of Crag Mammalian remains is preserved in the Ipswich Museum and is in the greater part due tothemunificence of a former President, Sir Richard Wallace, who purchased and presented the collection of the Rev. H. Canham, at one time rector of Waldringfield. Later other collections were purchased or bequeathed and new specimens have been added from excavations, coastal erosion or work in quarries.

Research prompted by the discovery of new material since the cessation of the " Coprolite Diggings" has shown that the mammalian faunas of the Red and Norwich Crags are very different from what has been generally supposed. The presence of elephant and equine remains, which are without question contemporary with the formation of the deposits, constitutes positive proof that the beds rightly belong to the EARLY PLEISTOCENE. It appears the Pleistocene epoch had endured for some unknown period prior to the rising sea level to which the formation of the Crag is due. Some of the Pleistocene mammalian fossils antedate the Red Crag and with the exception of a few cetacean bones all belong to land animals.

DĂźring the researches of J. Reid Moir (1911-42) for evidence of pre-Crag man at Bramford when mammalian fossils belonging to Whitaker's class (a) were discovered, it became apparent these unmineralised bones were contemporary with the formation of the Red Crag and were not derived from older deposits. The species from Bramford include a cetacean vertebra, a crushed and almost complete antler of Cervus (Euctenoceros) falconeri, Dawkins, basal portions of other shed antlers of the same species and part of an antler which was originally determined by C. W. Andrews (formerly of the British Museum [Natural History]) as C. tetraceros, Mackie.

Parts of shed antlers of C. (E.) sedgwicki and Damanestinesti were also discovered at Bramford. Since the very recent discovery of a more complete specimen of tetraceros at Wangford, nr. Southwold and the attachment of a long mislaid fragment of the first fossil, the determination appears to be inaccurate and the specimen resembles the upper bifurcation of an antler of the former species.

The inclusion of C. (E.) tetraceros in the Norwich Crag is founded on sundry specimens. These fossils remained in the Ipswich Museum for some twenty years before their true significance became apparent. A search among undetermined Crag bones in the Museum basement revealed other specimens which include an unprovenanced skull cap of a large deer, Megaceros verticornis, Dawkins, and the missing half of an upper third molar of Rhinoceros which fortunately, bore its label. These pieces were united and formed a nearly complete tooth, the only fossil of this genus apart from a vertebra from Dunwich, recorded from the Norwich Crag.

It was discovered at Sizewell and is a palaeontological puzzle, its

337 condi tion proves it to be a Crag fossil but it is more like the M3 of the Woolly Rhinoceros than any other Pleistocene species.

Until the families of this order are revised the specimen must remain a problem.

A number of more or less unmineralised specimens are preserved in the British Museum (Natural History) and in the Geological Survey Museum. It is possible there may be other, perhaps important fossils, lying unrecognised in various collections ; probably in the collection of Dr. Reed which is understood to be stored in a basement at York.

So far the only evidence of bovine remains are an indeterminate skull fragment from Holton Norwich Crag and several teeth from Red Crag, originally referred to Antelope (?) which are said by Dr. A. T. Hopwood to be Leptobos. However, the age of these is uncertain. Latterly efforts have been made to keep known mammaliferous sites under Observation and present indications imply that the term " Mammaliferous Crag " for the Norwich Crag is by no means undeserved when compared with the earlier Red Crag.

Only cetacean bones occur in the Coralline Crag. The metapodial and phalange recorded by E. T. Newton in " The Vertebrata of the Pliocene Deposits of Great Britain ", pl. III, f.7. as " Small ruminant, genus ? " from Gedgrave, are actually those of a recent sheep and are by no means fossil.

The mammals which make their first appearance in Britain occurring as fossils in the Red Crag are :— Elephant Elephas (Archidiskodon) meridionalis E. (Hesperoloxodoti) antiquus Zebra Equus (Hippotigris) robustus Horse Equus caballus Deer Cervus (Euctenoceros) falconeri C. (E.) sedgwicki C. (E.) tetraceros Dama nesti nesti Giant Deer Megaceros verticornis Gazelle Gasella anglica Fox Canis vulpes Wolf Canis lupus Hare Lepus sp.

Bear Ursus cf. arvensis The first eight mammals are recorded only from the middle (Newbournian) zone of the Crag which the relatively giant size of molluscan shells implies was the wärmest part of the epoch. In addition to the meridionalis teeth from Falkenham there is at Ipswich the major part of a tusk which is unprovenanced but has Crag material attached. Another tooth without data is more CRAG MAMMALS

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like E. (Hesperoloxodon) antiquus, falconeri but the specimen from the Crag figured in " Fauna Antiqua Sivalensis " by Falconer cannot now be traced. The deer falconeri appears to have been the most abundant, both in the Red and Norwich Crags and basal portions of shed antlers are in the three principal collections.

M. verticornis is recorded from Trimley and Felixstowe. Portions of antlers are at Ipswich and the British Museum (N.H.). The Anglian Gazelle is from Felixstowe, a horncore of the female being the only specimen known and an unprovenanced horncore of a male is also unique from the Red Crag. There are also some teeth and incomplete bones all preserved at Ipswich, one of which is from Martlesham.

The Norwich Crag yields fossil bones and teeth with greater frequency than the Red Crag ; this is partly due to the erosion of the Suffolk coast by the North Sea and to the exploitation for pebbles of the deposit at Holton. The section here shows Westleton marine pebble beds passing down conformably into Norwich Crag. Cetacean remains only have been found in the upper part but at 30 to 70 feet, which is partly below the water table, a fossiliferous zone has yielded abundant fragments of elephant bones, also cervid and equine remains. These occur with a good deal of driftwood accompanied by carboniferous erratics. A Jurassic reptilian limb bone has also been brought up by pumping. The fossils vary considerably in hardness, a few are mineralised with pyrite, in others above the water table any former pyriteous condition has been altered to limonite.

Some elephant teeth resemble those from the Cromer Forest Bed in appearance and some antler fragments are like those from the Red Crag whilst a few bones are very soft and exhibit no sign of mineralisation of any kind.

T h e Norwich Crag fauna includes :— Elephant Elephas (Archidiskodon) meridionalis Zebra Equus (Hippotigris) robustus Horse Equus caballus fossilis Deer Cervus (Euctenoceros) falconeri C. (E.) sedgwicki C. (E.) tetraceros Dama nesti nesti Dama cf clactoniana Elk Libralces gallicus Giant Deer Megaceros verticornis Gazella anglica Beaver Castor sp.

Microtines Various spp.

339

CRAG MAMMALS

East Anglian Succession

Epochs

UPPER PLEISTOCENE

Hunstanton Glaciation Ipswichian Interglacial Gipping Glaciation Hoxne, Clacton, Swanscombe Interglacial Lowestoft Glaciation Corton Interstadial Cromer Glaciation

MIDDLE PLEISTOCENE

Cromer Forest Bed Series Weybourne Crag Norwich Crag—high sea level—150' Red Crag—high sea level—150' Pre-Red Crag

LOWER PLEISTOCENE

Continental

phase

Pre-Red Crag Glaciation—low sea level Destruction of older rocks

PLIOCENE

Marine Coralline Crag partly denuded Continental deposits entirely destroyed

MIOCENE

? Miocene Marine deposits entirely denuded

EOCENE

Marine London Clay partly denuded Reading Clay Thanet Bed

CRETACEOUS

Chalk

Fig. 1. T h e succession of geological events suggested by the evidence observed in temporary and natural sections in south and east Suffolk during the past quarter of a Century.

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Bcaver is indicated by part of an incisor. Five basal fragments of antler of C. (E.) sedgwicki, are known ; one is in the British Museum (N.H.) another in the Geological Survey Museum and three at lpswich which proves this polycladine deer appeared long before the Forest Bed period. There are a number of broken tines. Dama and Libralces are new records for SufFolk and possibly for the older Crag.

Only one rather rolled microtine tooth is known from the Red Crag, it is provisionally referred to Mitnomys sp. Vole and other rodent teeth appear to be fairly abundant in the Norwich Crag but require much patient sifting to collect and it is possible that an intensive search in the Red Crag may yield a richer rodent fauna than is at present indicated.

Reference has been made to a pre-Red Crag glaciation ; the evidence for this is not abundant but many facts point to the later Crags as inter-glacials (Fig. 1). Work done by the Cambridge University Sub-Department of Quaternary Research has shown by pollen analysis and other evidence from a bore through the Norwich Crag at Ludham, that the deposits were laid down during a climatic fluctuation from cool to warm and cooling again toward the end of the period. A very low sea level, minus circa 170 feet, is indicated for an interval preceding the Norwich Crag epoch.

Early theories to account for the presence of far-travelled erratics below the Red Crag invoke the transport by ice-floes. The oldest Red Crag is at Walton-on-Naze, Essex, where Neptunea contraria is one of the abundant molluscs ; a species which thrives at the present time on the Spanish coast, the North Sea proving too cool today. This factor implies that the sea during " early " Crag times was at least as warm as the present Mediterranean Sea and it seems unlikely ice would have moved so far into a warm latitude before melting. Another point is the presence of striated flints and flints with " Basket patina", resembling those from the chalky glacial tills of East Anglia, in the basal beds of the Red Crag. These have also been accounted for by " grounded ice " but they are more likely to have been transported by land ice, the tili of which was destroyed by the incursion of the sea which rose to a height of over 150 feet above the present level.

The pre-Red Crag land surface was eroded and the whole of the London Clay was removed in places, (Bramford, Belstead and Gyppeswyk Park, lpswich) where the Crag rests on the Reading Beds. Most of the formerly much more extensive Coralline Crag was destroyed and a great deal of the Bryozoan material incorporated in the new formation.

341

CRAG MAMMALS

1 Species Elephas (Archidiskodon) meridionalis Equus robustus E. caballus

Red Norwich Crag Crag X

X

X X

Megaceros verticornis Cervus (Euctenoceros) falconeri C. (E). tetraceros

X

X X X X

X

X

X

C.

X

X X

E.

caballus fossilis

(E.) sedgwicki

Dama nesti nesti Libralces gallicus Gazella angelica G. daviesii

—

—

X

—

X

X

X X

Canis lupus C. vulpes

\

—

X

—

Lepus timidus

X

Castor sp.

X

X

Trichechus huxleyi Cetacea (spp. indet.)

X

X

X

X

I

_

2. A list of the principle mammals which are proved to have lived d 11 ring the Red and Norwich Crag periods. As the marnmalian fossil s of the Weybourne Crag have not been preserved together as a series it has not been possible to include them for comparison.

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The change in sea level recorded by Prestwich (1871) in the Quaternary Journal of the Geological Society, vol. XXVII, pl. 6, and indicated by the two beach levels in the Coralline Crag cliff at Sutton has been ignored by later workers. It would be expected the greater depth of the Red Crag Sea must have caused changes in the molluscan fauna which should be detectable by specialist investigation, but no work has been done. A much rolled pedicle of a deer (cf. C. (E.) falconeri) from the upper part of the Bawdsey Cliff may be associated with the reduced area of the Coralline Crag island which was restricted to a few acres (Fig. 2). The Newbournian (middle) Red Crag appears to have been more favourable climatically than the Waltonian as the shells of many species grew to a much larger size, but in the Butleyan zone (the upper or latest Red Crag) the shells are smaller and a number of cold species occur. Most fossils are without data regarding the horizon within the Crags from which they were collected in bygone years and at the present time the collection of bones or teeth in situ would appear to be most unlikely. There is, however, a possibility of securing pollen samples from the Holton mammaliferous horizon, from which driftwood samples of oak and conifer have been obtained. A quantity of fragments of limb bones of elephants, zebras and deer have been collected from this pit and thanks are due to the co-operation of the owner Mr. R. C. Norman and the diligence of the workers.

At Holton the Westleton Marine shingle beds, which are a series of buried beaches, pass down conformably into Norwich Crag and extend eastward some six miles to the coast at Southwold.

The series of beds forming the deposit are nearly two hundred feet thick. It is evident they extend some distance westward and a study of well boring records is necessary to prove this. T h e Red Crag also has its pebbly beach deposit which was first recognised by the author at Battisford where it is buried below glacial deposits and rests on chalk ; the thickness is about twelve feet.

Casts and impressions of shells in the upper part prove the former fossiliferous character of the whole bed. Shells are preserved in a fragile condition in the lower levels and teeth of sharks and much rolled bone fragments also occur. Without fossils it would be very difficult to correlate the Crag pebble gravels with other so-called Pliocene gravels which extend south-westward across the country.

Finally, the teeth of meridionalis from Dewlish in Dorset, which have hitherto been referred to the Cromer Forest Bed age, in all probability belong to the Red Crag, or less likely the Norwich Crag which seems to have had a lower basal sea level.

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343

Map of part of East Suffolk showing sone principle Crag localities.

The arrows indicate maamaliferous sitea.

Appendix On Saturday, 12th October, 1963, on the occasion of a visit of some members of Southwold W.E.A., one of the workers at the Holton Pit produced two pieces of a large tusk of the prehistoric

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Walrus, Trichechus huxleyi, Lankester. This discovery led to a re-examination of the series of Walrus tusks from the Red Crag in the Ipswich Museum. These had not been examined with the series of fossils considered to belong to the Crag fauna proper as they were thought to be derived from older deposits destroyed by the Red Crag Sea. The fact is most of the incomplete teeth are very heavily mineralised and are erratic fossils from the Red Crag Basement Bed. However, a nearly complete tusk, of which the fragile hollow base is preserved and is filled with comminuted shelly Crag is in Ipswich Museum. This evidencc constitutes strong proof of the existence of the Walrus during the the Red Crag epoch which forms a link between the pre-Crag Trichechus and the Fossil now known from the Suffolk Norwich Crag and the Cromer Forest Bed. Therefore T. huxleyi should be included in the fauna list given in the foregoing paper. It is believed this is the first record of the Walrus from the Suffolk Norwich Crag.

A vertebra provisionally identified as Rhinoceros sp. has also recently been discovered in the Norwich Crag of Easton Bavents cliff.

The previous records of Rhino from this deposit are a vertebra from Dunwich cliff nearly a Century ago and a tooth from Sizewell Over half a Century earlier than the present discovery.

It would appear that while a species of Rhinoceros lived in this region during the Crag period it must have been rare.