July, 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



179 



gether in the museums at Cape Town, Graham's Town, 

 and Albany. Among other energetic collectors, special 

 reference must be made to the late Dr. W. G. Ather- 

 stone, who devoted much time to the advancement of 

 our knowledge of South African geology and palaeonto- 

 logy, and to Mr. Alfred Brown, of Aliwal North, the 

 possessor of a magnificent collection of fossil reptiles, 

 the result of over forty years' assiduous labour. 



Although Professor Owen was the first to describe 

 and name the remains of these extinct reptiles, several 

 other workers have followed him in this line of investiga- 

 tion. A foremost place must be assigned to Professor 

 H. G. Seeley, F.R.S., who made a journey to South 

 Africa for the express purpose of collecting specimens 

 and studying those in the local museums, and who 

 subsequently published the results of his investigations 

 in the "Philosophical Transactions." The relations 

 of these reptiles to mammals formed the leading feature 

 in Professor Seeley 's investigations. More recently 

 Dr. R. Broom, now resident In South Africa, has 

 studied the nature of these fossils. 



Soon after the first representatives of the reptilian 

 remains were obtained it was recognised that the 

 rocks in which they were entombed formed an ex- 

 tensive series of freshwater deposits, for which the 

 distinctive title of Karoo system was selected; the chief 

 reptile-bearing horizons being those known as the Beau- 

 fort and the Stomberg beds. It should be added that 

 in addition to the remains of reptiles, these beds con- 

 tain ferns of the genus Glossopicris, and that fresh- 

 water deposits similarly containing Glossopicris, and in 

 some cases also Dicynodont reptiles, have likewise been 

 met with in India, Australia, and Argentina. Hence it 

 has been inferred that in early times the so-called 

 " Glossopteris flora," with its associated animals, 

 formed a zone round the world, lying to a great extent 

 in low latitudes. 



The next question was to determine the age of the 

 Karoo system and its equivalents in other parts of the 

 world. As the result of much discussion, it is now 

 generally admitted that this corresponds in the main 

 with the Trias, or Upper New Red Sandstone of 

 Europe, although some of the lower beds in the series 

 may represent the underlying Permian, or the beds 

 which, in Europe, immediately overlie the Coal- 

 Measures, and thus form the uppermost division of the 

 Paleozoic system, as the Trias constitutes the base of 

 the Mesozoic. 



The rocks of the Karoo system consist for the most 

 part of more or less merely horizontal strata of sand- 

 stones and shales, ranging from 8,000 to 10,000 feet in 

 thickness, and extensively traversed by outflows of 

 igneous rocks. These intrusive sheets consist of the 

 rock known as dolerite, and form flat table-lands rising 

 above the general level of the Karoo, giving rise to 

 the numerous "Tafelbergs" (table-mountains) to be met 

 with in this part of South Africa. 



It now remains to consider briefly the special features 

 of the South African Karoo reptiles which render them 

 of such remarkable interest and importance to the evolu- 

 tionist. In this connection it has to be mentioned that 

 there is a certain amount of difference of opinion in 

 regard to the best collective name for these reptiles. 

 In one of his earlier papers. Professor Owen proposed 

 the name " Anomodontia " for the Dicynodonts and a 

 certain British extinct reptile with which they have no 

 real affinity. In a later work (" Paleontology ") pub- 

 lished in 1861 this name was, however, taken to include 

 not only these Dicynodonts, but also the carnivorous 



types, although the definition was retained in the 

 original sense as being applicable only to the 

 Dicynodonts and associated forms. 



According to modern views, these Anomodont reptiles 

 represent a branch of reptilian stock (the Thero- 

 niorpha), equal in value to a second branch 

 (Ornithomorpha), which includes all other reptiles both 

 living and extinct. This indicates succinctly the real 

 importance of the Anomodonts, which seem to have 

 been derived from the earlier Permian salamander-like 

 creatures known as Labyrinthodonts, and which have 

 certainly given origin to mammal's. On the other 

 hand, the second reptilian branch, which gave origin 

 to birds, seems to have sprung from an entirely 

 different group of primeval salamanders — the Micro- 

 saurians. It should be added that it is to the egg- 

 laying mammals of Australasia (Monotremata), as 

 represented by the duckbill or platypus, and the echidna 

 or spiny anteater, that the Anomodont reptiles present 

 the closest resemblance. These egg-laying mammals 

 are, however, evidently specialised and aberrant forms, 

 and it is, consequently, to their extinct and more 

 generalised ancestors (which we may never discover) 

 that we must look as constituting the direct links be- 

 tween reptiles and mammals. Still, as it is, the 

 connection between the two groups is so close that 

 some of the Anomodonts have actually been described 

 as mammals. 



To render the resemblances existing between 

 Anomodonts and the Monotreme mammals apparent to 

 the general reader, without the aid of illustrati\e dia- 

 grams, is, of course, a difficult matter. It may be 

 mentioned, however, that the transition between the 

 complex lower jaw of an ordinary reptile, articulated to 

 the skull by means of a quadrate-bone, and the simple 

 jaw of a mammal, which has no such intermediate con- 

 nection, is exhibited by the Anomodonts; which also 

 show how the tripartite knob, or condyle, forming the 

 articulation of the skull with the vertebral column, 

 passes into the paired knobs, or condyles, of the 

 mammal. The bones of the pelvis and shoulder-girdle 

 (shoulder-blade, coracoid, etc.), are, again, essentially 

 similar in Anomodonts and Monotremes, and quite 

 different from those of other reptiles; and a similar re- 

 semblance is noticeable in the form and perforations of 

 the humerus or arm-bone, and in regard to the struc- 

 ture of the wrist and ankle joints. In a word, the 

 difficulty is, not to discover resemblances, but to point 

 out differences between the Anomodonts and the Alono- 

 tremes, although the more typical representatives of the 

 latter are undoubtedly reptiles in the strictest sense of 

 that term. 



Anomodonts are divisible into the following distinct 

 groups. First, the Dicynodonts, in which the males 

 (Dicynodon) are typically provided with a single pair 

 of tusks in the upper jaw, while the females (Udenodon) 

 were toothless; other forms having, however, crushing 

 teeth on the palate; secondly, the Carnivorous, or 

 Theriodont, type, like Galesatinis, in which the whole 

 skull and dentition is marvellously manmial-like; 

 thirdly, the Cotylosauria, in which the hinder part of 

 the skull was partly roofed over; and, fourthly, the 

 Pariasauria, in which the whole skull was roofed and 

 its bones sculptured, so that the resemblance to a 

 labyrinthodont salamander becomes exceedingly close. 

 Some of these creatures, notably Pariasaurus, certain 

 species of Dicynodon, and a few Theriodonts, were of 

 enormous bodily size — as large as crocodiles. 



