PALÆONTOLOGY
Among many other claims to the best attention of the
student of vertebrate palæontology, Somerset has a special
pre-eminence on account of having yielded the earliest known
evidence in Britain of the existence of mammals. Indeed,
there are no earlier representatives of the group known from any part
of the world. In referring the remains in question to the Mammalia
it must however be borne in mind that they may prove to belong to
creatures intermediate between reptiles and the living duckbill (Ornithorhynchus anatinus) of Australia, which is one of the two lowest existing
mammals. These presumed mammals are known only by teeth and are
assigned to a genus (Microlestes) originally described from the Trias of
the continent, but to species different from the continental. Certain
of these teeth, now in the Bath Museum, were obtained from a fissure
in the Rhætic strata of Frome, and named by Sir R. Owen Microlestes
moorei, in honour of Mr. C. Moore, the well known collector of
Somerset fossil vertebrates. Another tooth, preserved in the museum at
Oxford, was collected by Professor W. B. Dawkins in the Rhætic of
Watchet, and named by him Hypsiprymnopsis rhæticus, on the supposition
that it indicated a creature allied to the modern rat-kangaroos of Australia. It appears however to be undoubtedly referable to the same
genus as the Frome specimens, if indeed it be specifically distinct. If,
as is stated to be the case, it was found in undisturbed Rhætic strata it
is of the highest importance as definitely fixing the Triassic age of the
former. For as the Frome teeth were obtained from a fissure in the
Rhætic, it is obvious that they might perfectly well be of post-Triassic
origin.
Leaving then these highly interesting teeth, we pass on to the
consideration of the fossil fish of Somerset, among which several are
peculiar to the county. The oldest of these occur in the Carboniferous strata of the county, (fn. 1) where they are represented by Cladodus
mirabilis, a primitive shark of the group Ichthyotomi. Among the
true sharks (Selachii) a tooth from Clevedon in the British Museum
belongs to the well known Psammodus rugosus, whose large pavement-like crushing teeth are common in Carboniferous strata. Other teeth
from Clevedon have curved and elevated crowns, and belong to Delto
ptychius gibberulus, a member of the family Cochliodontidæ. The Carboniferous strata of the same locality have likewise yielded numerous teeth
referable to Orodus ramosus, a pavement-toothed shark belonging to
the family (Cestraciontidæ) typified by the existing Port Jackson shark.
The formations newer than the Carboniferous have yielded a large
number of peculiar fishes, one of the most interesting being Diplodus
moorei (fn. 2) from the Keuper, which is only known from Somerset, and
indicates the survival in the early Secondary of the Palæozoic cladodont
type (Ichthyotomi). Specimens from the Rhætic strata of the county
indicate the occurrence of Hybodus minor, a fairly common cestraciont
shark. Among species of uncertain affinity described on the evidence
of fin-spines, the one known as Nemacanthus monilifer is indicated by
a small spine from the Rhætic of the county. Other Rhætic fishes are
the ganoid Sargodon tomicus and Saurichthys acuminatus, both of which
have a wide distribution.
From the lower Lias three species are known, namely the pavement-toothed shark Acrodus nobilis, of which teeth (termed by quarrymen in some parts of the country fossil leeches) and fin-spines are met
with at Weston and Keynsham near Bath ; the ganoid Pholidophorus
stricklandi, of which remains occur at Glastonbury (the only other
locality for the species being Leicestershire); and another ganoid,
Mesodon liassicus, which is known from Langport.
Special interest attaches to the Upper Liassic fishes of Ilminster,
a fine series of which, now in the Bath Royal Literary and Scientific
Institution, were collected by the late Mr. C. Moore. These specimens
have been described by Dr. A. Smith Woodward in a paper contributed
to the Proceedings of the Bath Club. (fn. 3) They belong to a zone in the
Lias represented elsewhere in Würtemberg, Bavaria, Calvados and Vassy
in France, and Whitby in Yorkshire.
The first is a ganoid, Lepidotus elvensis, originally described from
Würtemberg, and belonging to a well known genus in which the
crushing teeth are button-shaped and the polished scales large and
rhomboidal. Fragments too imperfect to admit of specific determination indicate the occurrence of a representative of another ganoid genus,
Dapedius; but of much more interest is a fine and apparently unique
specimen of an unnamed species of the genus Caturus, which occurs
typically in the lithographic limestones of Bavaria. The special interest
of Caturus, as remarked by Dr. Woodward, consists in its being almost
identical in regard to the structure of the head, skeleton and fins with
the rhombic-scaled Eugnathus, although its whole body is invested with
thin overlapping scales. The most numerous of the Ilminster fishes
belong however to the Mesozoic ganoid genus Pachycormus, which
represents a family whose members present a curious superficial resemblance to the modern sword-fishes; the Cretaceous Protosphyræna being
one of the Pachycormidæ in which a true sword was developed. The
Ilminster species apparently include the typical Pachycormus macropterus,
the smaller P. curtus, P. esocinus, and an unnamed small-scaled form.
Other remains suggest a species which may belong either to Pachycormus
or the allied genus Saurostomus, while a head in the British Museum
belongs to a species of Pholidophorus, perhaps identical with P. germanicus
of Würtemberg and Whitby. Leptolepis bronni, a more modern type
of ganoid, is also met with at Ilminster.
From the Great Oolite of the county teeth of two common
Mesozoic sharks, Strophodus magnus and Hybodus grossiconus, have been
obtained, both belonging to the family Cestraciontidæ; and also the ganoid
Lepidotus tuberculatus. In the Upper Greensand of Kilmerton we have
a more modern type of shark represented by a tooth in the British
Museum referable to the common Cretaceous Oxyrhina mantelli. (fn. 4)
Of the fossil reptiles of Somerset, one of the earliest appears to be
the small carnivorous dinosaur Thecodontosaurus platyodon, of which
there are two teeth in the British Museum from the upper Trias of
the county. This species is typically from the Trias of Bristol, but
other dinosaurian remains from the Rhætic of Wedmore near Glastonbury have been considered to represent two genera and species peculiar
to the county. These have been named (fn. 5) Avalonia sanfordi and Picrodon
harveyi, but further evidence seems desirable to show their distinctness
from one another and also from the widely spread Triassic genus
Zanclodon.
Remains of large marine saurians belonging to the genera Ichthyosaurus, Plesiosaurus, etc., are exceedingly abundant in the lower Liassic
strata of Bath, Glastonbury, Street and Watchet, where many more or
less nearly entire skeletons have been obtained. A fine series of such
specimens are exhibited in the British Museum, several of which are
the types of the species they represent. Ichthyosaurs, it may be mentioned, have very large heads, short necks, paddles composed of a
number of polygonal bones articulated together to form a pavement, and
the bodies of the vertebræ very short, deeply cupped, and quite separate
from the arches protecting the spinal cord. Some of them reach thirty
feet in length, and all have a ring of bones in the white of the eye.
Most of the species from the county belong to the group with broad
paddles, among them being Ichthyosaurus communis from Bath and Street,
I. conybeari from Saltford near Bath, and I. intermedius from Street. The
very distinct and gigantic I. platyodon is common in the county, and
there are certain bones from Watchet in the Boulogne Museum which
may indicate yet another species of the genus.
The Liassic plesiosaurs differ from the ichthyosaurs not only by
their elongated necks and small heads, but likewise by the structure of
their paddles, the bones of which are of normal form and do not make
a pavement. The bodies of the vertebræ too are relatively longer, less
deeply cupped, and more firmly articulated to the arches, while there
are no ossifications in the ball of the eye. Plesiosaurus compressus has been
met with in the lower Lias of at least one locality in the county. P.
dolichodirus occurs at Bath and Watchet, P. hawkinsi at Street, and P.
macrocephalus at Street and at Weston near Bath. The species Plesiosaurus
eleutheraxon was named from remains found at Street, and vertebræ from
the same locality have been made the type of a nominal species under
the name of P. subconcavus, while others from Weston have been
described as a second nominal species with the title of P. subtrigonus.
Of the allied genus Thaumatosaurus, distinguished by the proportionately
larger head, two species occur in the lower Lias of the county, namely
T. arcuatus and T. megacephalus. Part of a lower jaw in the British
Museum, which is probably from Street, forms one of the types of the
former species, of which remains also occur at Bath. The second
species is typified by an entire skeleton in the British Museum from
some locality in the county.
Reptilian remains from other Mesozoic deposits appear to be rare
in Somerset. A peculiar species of long-nosed crocodile of the genus
Steneosaurus is typified by a skull from the Great Oolite of Bath described
by Sir R. Owen as S. temporalis. The common Cretaceous Ichthyosaurus
campylodon is represented in the county by teeth and vertebræ from the
Upper Greensand of Kilmerton; (fn. 6) and a large-headed representative of
the pliosaurs occurs in the lower Chalk of Frome in the form of the
widely spread Polyptychodon continuus.
As regards Tertiary Mammalia, Somerset is celebrated on account
of the large number of remains obtained from the limestone caves of the
Mendips, of which a magnificent series are preserved in the Museum
of the Somerset Archæological and Natural History Society at Taunton. (fn. 7)
The earliest of these caves to be explored was that of Hutton near
Weston-super-Mare, which was known to contain bones so long ago
as the middle of the eighteenth century. This cave, together with the
neighbouring ones of Banwell, Bleadon, Goat's Hole in Barrington
Combe, Sandford Hill and Uphill were explored by Messrs. Beard and
Williams between 1821 and 1860, while the so-called hyæna den of
Wookey Hole, on the south side of the Mendips near Wells, was
worked in 1859 and following years by Professor W. B. Dawkins and
others. It was one of the first caverns in England where articles of
human manufacture were found in association with the remains of
extinct mammals. In addition to the abundance of hyænas at Wookey
Hole, the Mendip mammalian fauna is especially characterized by the
number of remains of lions, as it likewise is by a few indications of the
presence of the wolverine, or glutton, an animal scarce in British Pleistocene deposits.
Among the Carnivora from the Mendip caverns may be mentioned
the Pleistocene lion (Felis leo spelæ), which occurs at Banwell, Bleadon,
Sandford and Wookey, the leopard (F. pardus) from Banwell and
Bleadon or Hutton, the wild cat (F. catus) at Bleadon, the Egyptian
cat (F. maniculata), the Pleistocene variety of the spotted hyæna (Hyæna
crocuta spelæa) from Banwell, Bleadon and Wookey, the wolf (Canis
lupus) and fox (C. vulpes) from Banwell, Bleadon and Sandford, the otter
(Lutra lutra) from Banwell and Bleadon, the badger (Meles meles)
from Banwell and Wookey, the marten (Mustela martes) from Bleadon,
the wolverine (Gulo luscus) from Banwell and Bleadon, the brown bear
(Ursus arctus), including the so-called grizzly, and the great cave-bear
(U. spelæus).
The Somerset cave rodents, according to Mr. W. A. Sanford, (fn. 8)
include the common hare (Lepus europæus), mountain hare (L. timidus),
Pleistocene hare (L. diluvianus), Siberian hamster (Cricetus songarus),
water-vole (Microtus amphibius), field-vole (M. agrestis), bank-vole
(Evotomys glareolus), Norwegian lemming (Lemmus lemmus), banded
lemming (Dicrostonyx torquatus), an apparently extinct species of suslik
(Spermophilus erythrogenoides), and the common pica (Ochotona pusilla).
Another vole, Microtus ratticeps, has also been recorded from the
caves of Somerset ; this being apparently the only known instance of
the occurrence of this continental species in Britain.
Among the hoofed mammals may be mentioned the Pleistocene
bison (Bos priscus), the wild ox (B. taurus primigenius), the red deer
(Cervus elaphus), giant fallow deer, commonly called 'Irish elk' (C.
giganteus), roe (Capreolus capreolus), reindeer (Rangifer tarandus), wild
boar (Sus scrofa), woolly rhinoceros (Rhinoceros antiquitatis), leptorhine
rhinoceros (R. leptorhinus), wild horse (Equus caballus fossilis), mammoth
(Elephas primigenius), and straight-tusked elephant (E. antiquus).
Remains of bats are rare in British caves, but bones provisionally
assigned to White's bat (Pipistrellus noctula) have been recorded from
Banwell and Hutton caves.
There are also certain Pleistocene deposits other than those in
caverns from which mammalian remains have been obtained in the
county. Teeth or bones of the horse have, for instance, been found in
a raised beach at Weston-super-Mare, as well as in superficial deposits
at Bath and Larkhall. The mammoth also occurs at the two localities
last-mentioned, while the straight-tusked elephant, woolly rhinoceros
and reindeer are recorded from Larkhall, and the wild boar from both
Larkhall and Ilminster.
Botanical Map