An introduction to the osteology of the mammalia : being the substance of the course of lectures delivered at the Royal College of Surgeons of England in 1870

Abstract

CLASSIFICATION OF THE MAMMALIA. [chap. The classification and the names of the subdivisions used throughout this work correspond, in the main, with those given by Professor Huxley in his " Introduction to the Classification of Animals," 1869. The whole of the animals composing the class are arranged primarily in three natural divisions, which, presenting very marked differentiating characters, and having no existing intermediate or transitional forms, may be considered as sub-classes of equivalent value, taxonomically speaking, though very different in the numbers and importance of the animals composing them. Pecora y or true Ruminants, comprising the Deer, Giraffes, Antelopes, Sheep, Goats, and Oxen. The last three divisions constitute the order Ruminantia of Cuvier. 8. Hyracoidea, an order consisting of a single genus, Hyrax , a small animal having many affinities with the Perissodactyle Ungulata, with which it is often associated. 9. Proboscidia, represented at present only by the two species of Elephant and 10. Rodentia, a well-marked group, but with varied affinities, both to the Insectivora and Primates on the one hand, and to the Ungulata and Proboscidia on the other, and also to the Didelphia. This order contains the Hares, Rats, Guinea-pigs, Porcupines, Beavers, Squirrels, &c. II. The sub-class Didelphia comprises only one order, Marsupialia, consisting of animals presenting great diversity of superficial appearance and habits of life, although all united by many essential anatomical and physiological characters. skull, the sternum, and the ribs. CHAPTER III. THE VERTEBRAL COLUMN. General Characters .-The Vertebral Column consists of a series of distinct bones called Vertebrce , arranged in close connection with each other along the dorsal side of the neck and trunk, and in the median line. It is generally prolonged posteriorly beyond the trunk to form the axial support of the appendage called the tail. Anteriorly it is articulated with the occipital region of the skull. The number of distinct bones of which the vertebral column is composed varies greatly among the Mammalia, the main variation being due to the elongation or otherwise of the tail. Apart from this, in most Mammals, the number is not far from thirty, though it may fall as low as twenty-six (as in some Bats) or rise as high as forty (Ifyrax and Choloepus \ 1 The different vertebrae, with some exceptions, remain through life quite distinct from each other, though closely connected by means of fibrous structures which allow of a certain, but limited, amount of motion between them. The exceptions are,-near the posterior part of the trunk, in nearly all Mammals which possess completely developed 1 These numbers are not exact, owing to the uncertainty in the mode of reckoning the sacral vertebne. CHAP. III.] GENERAL CHARACTERS. n hinder limbs, two or more vertebrae become ankylosed together to form the " sacrum " the portion of the vertebral column to which the pelvic girdle is attached. As a rule, none of the other vertebrae are normally united ...

Shaping Skeletal Growth by Modular Regulatory Elements in the Bmp5 Gene

“…Nested sets of HOX gene expression are evolutionarily ancient programs used to pattern basic body axes in both vertebrates and invertebrates [44],[45],[47]. In contrast, both cartilage and bone are more evolutionarily recent, vertebrate-specific tissues that vary widely in form from species to species [1]. For example, respiratory nasal turbinates are thought to have arisen separately in bird and mammals to help conserve water during breathing [48]–[50].…”

“…Our studies suggest resegmentation also plays a key role in establishing detailed growth patterns in developing ribs (Figure 7). Although ribs are usually thought of as simple tubular structures, they can be extensively modified in different organisms to produce the diverse cross-sectional shapes, as well as the varied curvatures seen in wide- and narrow-bodied animals [1],[57]. It has long been recognized that differential deposition on the lateral surface of ribs must underlie the expansion and ultimate shape of ribs and thoracic cavities [3].…”

“…Individual bones can show striking morphological specializations in different species, suggesting that separate genetic mechanisms must exist for regulating the growth of skeletal tissue at highly specific anatomical sites in the body [1],[2]. Despite the importance of skeletal structures for support, protection, eating, breathing, and movement, the detailed genetic mechanisms controlling the shape and growth of individual bones are still poorly understood.…”

Evolving New Skeletal Traits by cis -Regulatory Changes in Bone Morphogenetic Proteins

“…Striking changes in vertebrate skeletal structures underlie interesting differences in locomotion, foraging, prey capture, competition, and body defense (Flower, 1870). BMPs are key signaling molecules that are known to be necessary, sufficient, and expressed at the right time and place to control local formation of bones and joints during normal development (Kingsley, 1994).…”

Postsacral Vertebral Morphology in Relation to Tail Length Among Primates and Other Mammals

“…The bony mammalian tail can be subdivided into three regions based on external vertebral anatomy: proximal, transitional, and distal ( Fig. 1 ;Flower, 1876;Schmidt, 1886;Ankel, 1965Ankel, , 1972German, 1982;Lemelin, 1995;Argot, 2003;Schmitt et al, 2005;Organ, 2007Organ, , 2010Organ et al, 2009;Russo and Young, 2011). Vertebrae in the proximal tail region typically possess a single pair of transverse processes and bear neural arches, articulating with one another by way of zygapophyseal and body joint surfaces.…”