Fossil Mammalia - Part I - The Zoology of the Voyage of H.M.S Beagle

Under the Command of Captain Fitzroy - During the Years 1832 to 1836

Richard Owen, Charles Darwin

• Publisher: Read & Co. Science
• Year: 2019
• Print ISBN: 9781528712088, 9781528771740
• eBook ISBN: 9781528787000
• Topic: Biological Sciences
• Subtopic: Evolution
• Index: Biological Sciences

Discover one of the foundational scientific works resulting from Charles Darwin's world-altering journey aboard H.M.S. Beagle.

This is Part I: Fossil Mammalia, which details the extraordinary fossil discoveries Darwin made, primarily in South America between 1832 and 1836. These specimens, collected in what Darwin called his "fossil fever," included the remains of giant, extinct creatures like the massive ground sloth Glossotherium, the rhino-sized ungulate Toxodon platensis, and the enigmatic Macrauchenia.

This volume presents the meticulous scientific descriptions of these fossils. The revelations contained within, particularly the discovery of extinct megafauna related to smaller, modern animals in the same region, played a crucial, formative role in the development of Darwin's theories on extinction, evolution, and natural selection.

A key piece of natural history and a testament to the scientific revolution sparked by the Beagle voyage, Fossil Mammalia offers a direct look at the evidence that would ultimately lead to On the Origin of Species.

Contents include:

• Toxodon Platensis, Description of Cranium
• Of Lower Jaw and Teeth
• Macrauchenia Patachonica
• Cervical Vertebrae
• Lumbar Vertibrae
• Scapula
• Antibrachium and Fore-foot
• Femur
• Tibia, Astragalus, and Metatarsal Bone
• Glossotherium, etc.

Description Of Parts
Of The Skeleton Of

Macrauchenia Patachonica;

A large extinct Mammiferous Animal, referrible to the Order Pachydermata; but with affinities to the Ruminantia, and especially to the Camelidæ.

IN the preceding pages the nature and affinities of a large extinct Mammal were attempted to be determined from the cranium and teeth exclusively: we come now to consider the remains of a quadruped consisting of bones of the trunk and extremities, without a fragment of a tooth or of the cranium to serve as a guide to its position in the zoological scale.

It may appear, even to anatomists and naturalists familiar with the kind of evidence afforded by a fossil fragment, that an opinion as to the relation of the present species to a particular family of Ruminants, formed without a knowledge of the important organs of manducation, must be vague and doubtful, but the evidence about to be adduced, will be regarded, it is hoped, as more conclusive than could have been à priori expected.

The portions of the skeleton of the animal—which, in relation to the affinity above alluded to, as well as from the length of its neck, I propose to call Macrauchenia*—were discovered by Mr. Darwin in an irregular bed of sandy soil, overlying a horizontal accumulation of gravel on the south side of Port St. Julian: and independently of the circumstances under which they were found, their correspondence with each other in size, colour, texture and general character prove them to have belonged to one and the same individual.

These remains include two cervical vertebræ, seven lumbar vertebræ, all more or less fractured; a portion of the sacrum and ossa innominata; fragments of the left scapula; of the left radius and ulna, and left fore-foot; the left femur nearly entire, the proximal and distal extremities of the left tibia and fibula; and a metatarsal bone of the left hind foot.

Before entering upon the description of these remains, a few observations may be advantageously premised on some of the distinguishing characters of the Camelidæ. It is well known that the Camels and Llamas deviate in their dentition, viz., in the presence of two incisors in the upper jaw, from the true Ruminants; and we cannot avoid perceiving that in this particular the direction in which they deviate tends towards the conterminous Ungulate Order, in which incisor teeth are rarely absent in the upper jaw. They also further deviate from the Ruminants and approach the Pachyderms in the absence of cotyledons in the uterus and fetal membranes; having, instead thereof, a diffused vascular villosity of the chorion, as in the sow and mare.8

But besides these characters, by which, in receding from one type of hoofed mammalia, the Camelidæ claim affinity with another, there are many parts of their organization peculiar to themselves; of some of these peculiarities, the relation to the circumstances under which the animal exists, can be satisfactorily traced; in others, the connection of the structure with the exigencies of the species, is by no means obvious, and in this predicament stands the osteological peculiarity, which is immediately connected with our present subject—a peculiarity in which the Camelidæ differ not only from the other Ruminants, but from all other existing Mammalia, and which consists in the absence of perforations for the vertebral arteries in the transverse processes of the cervical vertebræ, the altas excepted.

I may observe that what is described as a perforation of a single transverse process in a cervical vertebra is essentially a space intervening between two transverse processes, a rudimental rib, and the body of the vertebra. In the cold-blooded Saurians,—in which the confluence of the separate elements of a vertebra takes place tardily and imperfectly, if at all,—the nature of the so called perforation of the transverse process is very clearly manifested, as in the cervical vertebræ of the Crocodile, in which the interspace of the inferior and superior transverse processes is closed externally by a separate short moveable cervical rib. In the Ornithorhynchus paradoxus the vertebra dentata also preserves throughout life this condition of its lateral appendages: in other Mammalia it is only in the fœtal state that the two transverse processes are manifested on each side with their extremities united by a distinct cartilage, which afterwards becomes ossified and anchylosed to them.

In the Hippopotamus the inferior transverse process sends downwards a broad flat plate extended nearly in the axis of the neck, but so obliquely, that the posterior margins of these processes, in one vertebra, overlap the anterior ones of the succeeding vertebra below, like the cervical ribs in the Crocodile; the same structure obtains in many other mammalia, especially in the Marsupials. In the Giraffe, the inferior transverse processes are represented by relatively smaller compressed laminæ, projecting obliquely downwards and outwards from the anterior and inferior extremity of the body of the vertebra. The superior transverse processes in this animal are very slightly developed in any of the cervical vertebræ, and the perforation for the vertebral artery is above and generally in front of the rudiment of this process, being continued as it were through the side of the substance of the body of the vertebræ.

In the long cervical vertebræ of the Camel and Llama, the upper and lower transverse processes are not developed in the same perpendicular plane on the sides of the vertebræ, but at some distance from each other; the lower transverse processes (a, fig. 1, Pl. VI.; a, fig...

Table of contents

• Charles Darwin
• Preface.
• Geological Introduction.
• Fossil Mammalia.
• A Description Of The Cranium OfToxodon Platensis;
• Description Of Parts Of The Skeleton Of Macrauchenia Patachonica;
• Description Of A Fragment Of A Cranium Of An Extinct Mammal, Indicative Of A New Genus Of Edentata, And For Which Is Proposedthe Name Of Glossotherium.
• Description Of A Mutilated Lower Jaw And Teeth, On Which Is Founded A Subgenus Of Megatherioid Edentata, Under The Name Of Mylodon.
• Description Of A Considerable Part Of The Skeleton Of A Large Edentate Mammal, Allied To The Megatherium And Orycteropus, And For Which Is Proposed The Name Of Scelidotherium* Leptocephalum.
• Description Of A Mutilated Lower Jaw Of The Megalonyx Jeffersonii.
• Description Of A Fragment Of The Skull And Of The Teeth Of TheMegatherium Cuvieri.
• Description Of Fragments Of Bones, And Of Osseous Tesselated Dermal Covering Of Large Edentata.
• Notice Of Fragments Of Molar Teeth Of A Mastodon.
• Notice Of The Remains Of A Species Of Equus,
• Description Of Remains Of Rodentia, Including The Jaws And Teeth Of An Extinct Species Of Ctenomys.