|GEOLOGICAL AND PALEONTOLOGICAL
J. F. POMPECKJ AND FR. FREIH. VON HUENE
NEW SERIES, VOLUME 6
REVIEW OF THE REPTILIA OF THE TRIASSIC
FRIEDRICH VON HUENE*
WITH 78 TEXT-FIGURES AND 9 PLATES
GUSTAV FISCHER PUBLISHING HOUSE
The following compilation of Triassic reptiles arose as a by-product of the revision of the Dinosauria of the European Triassic. It was naturally necessary for me to learn about all the contemporaneous reptilian fauna. And indeed I went beyond Europe and brought the rest of the world into the range of my investigations, as far as was possible using the literature and friendly cooperation, especially of the American workers. I think I have seen most of the specimens in question that are preserved in the European collections. To this end I visited the following collections:
Anabach, Basel, Bayreuth (Kreismuseum and private collection of Herr STRUNZ), Berlin, Breslau, Bristol, Crailsheim (hon. BLEZINGER), Edinburgh (Museum of Science and Arts and Geological Survey), Elgin, Freiburg im Breisgau, Göttingen, Halle am Saale, London (British Museum, Jermyn Street Museum, and private collection of Prof. SEELEY), Milan, Munich, Oxford, Paris (Muséum d’Histoire naturelle and École des Mines), Poligny, Strassburg, Stuttgart, Tübingen, Vienna (Geological and Palaeontological Institute of the University, Hofmuseum and Imperial Geological Institute), Warsaw.
I take this opportunity of thanking the following gentlemen:
ABEL, von AMALITZKY, ANDREWS, von ARTHAEER, BASSANI, BECKENKAMP, BEECHER, von BISTRAM, BLEZINGER, BOLTON, BONVALLOT, BRANCO, BROILI, R. BURCKHARDT, DOLLO, DOUVILLÉ, E. FRAAS, FRECH, GAUDRY, GIRARDOT, JAEKEL, von KOENEN, KOKEN, LENK, LUCAS, MARIANI, E. T. NEWTON, von NOPCSA, OSBORN, PLIENINGER, SEELEY, SOLLAS, STEHLIN, STEINMANN, STRÜBIN, STRUNZ, TAYLOR, TRAQUAIR, UHLIG, WICKES, H. WOODWARD, A. SMITH WOODWARD, WUNDER, VYSSOGORSKI, von ZITTEL.
I have attempted to assemble as much material as possible but I realize that there is still much omitted. It was not my aim to attain absolute completeness nor to treat all the usable data exhaustively, but I am satisfied to show at least to some extent the wealth and diversity of the reptilian fauna of the Triassic. Therefore I also tried to illustrate this by as large a number of figures as possible, many of which are copies, partly to save the reader numerous references. Many well-known facts are repeated, other new ones are produced in addition, which is in keeping with the character of such a compilation that, in a way, attempts to combine the results of previous studies in this field.
All parts of the work are not dealt with in the same way, thus e.g. the section on the Dinosauria is made very short, although most new facts could have been stated here. But since I will publish a larger monograph on this subject in the near future, I will not anticipate it.
In many respects it was not possible for me to keep to the often far too schematic classification of paleontological textbooks. This will perhaps be most striking in the “Rhynchocephalia.” The Anomodontia are also interpreted in bounds rather different from usual. The thorny question of the relation between the Anomodontia and the Monotremata, or Mammalia in general, is not referred to at all, since I have not come to any satisfactory original opinion concerning it.
In the following, a number of new names are introduced, which are in part based on poor remains. This is only a last resort since it is more convenient to use names in discussion than to describe the piece each time.
Tübingen, 11th May 1902. Friedrich von Huene.
A. INTRODUCTION 5 (1)
B. THE EIGHT REPTILE ORDERS, WITH DISCUSSION OF INTERESTING AND NEW FORMS AS APPENDIX 6 (2)
1. “Rhynchocephalia” 6 (2)
Proterosaurus-like reptile from the Bunter Sandstone 8 (2)
2. Ichthyopterygia 10 (3)
3. Anomodontia (and Stegocephalia) 12 (4)
Trochanterium gaudryi n. gen. n. sp. 20 (8)
Eurycervix postumus n. gen. n. sp. 21 (8)
Crurosaurus problematicus n. gen. n. sp. 23 (9)
New observations on Sclerosaurus armatus H. v. M. 23 (9)
Vertebra of Placodus gigas 32 (13)
Psephoderma and Psephosaurus 33 (13)
Anomosaurus n. gen. div. sps. 33 (13)
Ctenosaurus koeneni n. gen. n. sp. 37 (15)
4. Sauropterygia 38 (15)
Presence of Plesiosauria in the Muschelkalk 44 (17)
Plesiosaurus priscus n. sp. 44 (18)
Peculiar sacral vertebra from the Muschelkalk 45 (18)
Plesiosaurus from the Upper Keuper and Rhaetic 45 (18)
Doliovertebra fritschi n. gen. n. sp. 47 (19)
5. Testudinata 48 (19)
Chelyzoon latum n. gen. n. sp. 50 (20)
Chelyzoon blezingeri n. sp. 51 (20)
On Arctosaurus osborni ADAMS 52 (21)
Vertebra from the Rhaetic 52 (21)
Chelonian remains from Busendorf 53 (21)
Femur inc. sed. 53 (21)
Humerus inc. sed. 54 (21)
6. Parasuchia (and Eusuchia as appendix) 54 (22)
New and misinterpreted Parasuchia 62 (25)
I. Belodon arenaceus E. FRAAS sp. 62 (25)
II. Rileya bristolensis n. gen. n. sp. 62 (25)
True (?) Crocodilia from the Lower Muschelkalk 63 (25)
True Crocodilia from the Upper Muschelkalk 64 (26)
I. Procerosaurus cruralis n. gen. n. sp. 64 (26)
II. Pectenosaurus strunzi n. gen. n. sp. 65 (26)
III. A lower jaw piece 65 (26)
7. Dinosauria 65 (26)
8. Pterosauria 65 (26)
C. SYSTEMATIC REVIEW OF THE TRIASSIC REPTILIA 67 (27)
D. DISTRIBUTION AND IMPORTANCE OF THE TRIASSIC REPTILIA 73 (28)
The reptilian fauna of the Triassic claims great interest since it includes nearly the oldest representatives of this vertebrate class and yet consists of very different elements. The attractiveness of this picture is increased further by the fact that the extremely diverse and well-known reptilian fauna of the Jurassic and Cretaceous is derived from that small vestige only by a comparatively limited evolutionary change. The distance to the Permian is much larger, since many orders had still not appeared there in the Triassic. The Permian characters are still recognizable and the Jurassic ones are already present.
When all the data are gathered, it is very surprising how many reptiles are included in the Triassic fauna; it is sufficient to quote the number of 153 genera (excluding synonyms). All orders represented in the Jurassic are already present and in addition there are the remarkable Anomodontia and the very interesting group Parasuchia standing between Crocodilia and Dinosauria. The Stegocephalia also play an important role, successors from the Permian which are almost entirely absent in the Jurassic (1). On the other hand, in the upper Mesozoic the first small mammals and the birds appear. The many small anomodonts of the South African Triassic and Central Europe (Microlestes, etc.) may well have recalled the former in appearance and mode of life.
We are in rather a good position to form an idea of the higher vertebrate fauna of the Triassic. Neither the dry land nor the water were more sparsely populated than at present in the regions which man has not yet devastated by his cultural efforts. Certainly today there are animals living so entirely differently that it is difficult to form a graphic conception of this fauna. We shall certainly find some creatures that, by our knowledge of recent animal populations of the earth, could appear to us as old friends by their external morphology. A number of large and small crocodile-like animals and some rare turtles belong here. But now a multitude of more or less strange forms follow, some downright fantastic. In the coastal seas the rapacious Nothosauria, etc. in all possible sizes swim with paddling movements; the long swan-neck gave them quite a strange appearance. These are reproduced on a larger scale in the contemporaneous Plesiosauria; the body short, squat, broad, flat; on it a short thick tail and a neck as long as the thorax and tail together; the small head armed with pointed long teeth, the four adapted paddle-like limbs, long, broad and pointed at the end. Likewise in the salt water some Ichthyosauria moved, forerunners of the fish-like reptiles which populated the sea in large herds in the succeeding Liassic period. In the fresh water and its surroundings lived the very numerous crocodiles, among which the long-snouted forms, such as Mystriosuchus in particular, were predestined to grub for food in the mud like the present-day gavial. These crocodiles attract attention by their strong and sometimes beautifully decorated armor. The peculiar Stegocephalia mostly stayed in swamps and near water. They are generally ranked with the Amphibia which include today the insignificant frogs and salamanders. But these strongly armed monsters equipped with formidable teeth are very different from them; the head alone in many was almost 1 m long. Also the Pterosauria, which can be compared with the remotely related bats, are not quite absent from the Triassic.
The two groups remaining are the most extensive and important, namely Dinosauria and Anomodontia. They populated especially the land. Dinosauria (i.e. in this case, Theropoda), whose length varies from 2 to about 10 m, had a heavy, large body, long neck and tail, very strong, large hind legs and small, but muscular forelimbs which were probably used occasionally for locomotion and support of the body, but mainly for the seizing and holding fast of prey. The extremely small head must also have given these strange beasts a highly peculiar appearance. More than 20 different genera of dinosaurs compete in the strangeness of their body structure. Some of them are distinguished by an extremely long, flexible neck and tail (Tanystrophaeus); its belly was greatly distended and supported by bones (pubis); thus when it lowered itself it could rest on the ground and then be used as a support.
Anomodontia is composed of animals very different in appearance. Their size ranges from that of an ox to that of a mouse. In general they are stoutly built, have a large head, short neck and relatively long legs. Their teeth sometimes recall reptiles, sometimes mammals. According to their mode of life and appearance, we find among them large carnivores, small insectivores, fat rodents and stout herbivores, even the turtle-like Placodontia number in their ranks. They populated particularly the great continents, grown over with the Glossopteris flora with their rivers and lakes as well as the salt water of the coast.
After we have briefly compiled information on the extent of the Triassic Reptilia, it will he of value to discuss the most important data and points of comparison of the particular groups, in order to combine the results for an overall view.
B. THE EIGHT REPTILE ORDERS,
WITH DISCUSSION OF INTERESTING AND NEW FORMS
AS AN APPENDIX TO EACH SECTION
In textbooks Rhynchocephalia are placed at the head of Reptilia. The order Rhynchocephalia will include, by common characters:
1) Proganosauria (essentially Palaeohatteria and Proterosaurus),
3) Rhynchosaurus and Hyperodapedon,
5) Pleurosauridae (i.e. the elongated Jurassic forms Homoeosaurus, Pleurosaurus, Sapheosaurus, Sauranodon, etc.),
6) Champsosaurus, and
The differences between Proterosauridae and the genera of the Upper Jurassic or Rhynchosauridae and Hatteria are obvious. I think it is practical henceforth to detach Proganosauria as a separate group, for they have closer relation with Crocodilia and Dinosauria and with many Anomodontia and in several points with Stegocephalia (cf. e.g. pelvis). This may be dealt with in more detail elsewhere. Rhynchosaurus and Hyperodapedon, the Rhynchosauridae, are a very specialized group which deviates widely from Proganosauria. Their dentition is highly adapted to a specific way of life and recalls to some extent Endothiodontidae. The structure of the premaxilla nearly makes these forms degenerate. Rhynchosaurus recalls Ornithosuchus somewhat in the form of the head, thus a parasuchian; also its scapula is very crocodile- or dinosaur-like. But otherwise, particularly in Hyperodapedon, there is much similarity with therosuchian Anomodontia. The long transverse processes of the caudal vertebrae are not unlike those of Pareiasaurus. According to R. BURCKHARDT (1), both these genera are most closely related to the Endothiodontidae, which in their turn occupy a rather isolated position among Therosuchia. The vertebrae of Rhynchosauridae should be opisthocoelous, as well as the several Proganosauria. They have less in common with true Rhynchocephalia of the Mesozoic and the present day and are definitely to be separated from them.
The Mesosauria, which likewise often figure as Rhynchocephalia, occupy a most interesting central position between Anomodontia and Sauropterygia (particularly Plesiosauria). The whole structure recalls the latter very much. The distally expanded humerus shows an entepicondyloid foramen, like Nothosauria. The limbs are still developed as walking feet. The lower leg recalls Archegosaurus in that tibia and fibula diverge strongly and are curved outward as in the former. Astragalus and intermedium are fused, the calcaneum is separate; if one thinks this is also fused, the first tarsal row would resemble Pareiasaurus and Sclerosaurus most; the outline is the same. (On Mesosauria, cf. the sections on Anomodontia and Sauropterygia.) Further connections exist with Proganosauria, but those to Anomodontia and particularly Sauropterygia are so great that one is best to regard them as South African and American forerunners or representatives of the latter in the Triassic.
Finally, Telerpeton from Elgin still remains as a Triassic rhynchocephalian. It has absolutely nothing to do with Rhynchosauridae and Mesosauridae. However, as far as is known, it seems that true Rhynchocephalia of the Mesozoic and kionocrane Lacertilia stand closer. A glance at the pelvis and the posterior half of the skull, particularly the quadrate, suffices to produce this impression. Telerpeton is very lacertilian-like. But the pelvis also rather recalls Eryops. It is not at all impossible that a direct connection exists between the temnospondylous Stegocephalia and Telerpeton and from here to Mesozoic Plesiosauridae, etc. and Hatteria.
The important studies of OSAWA, SCHAUINSLAND, and HOWES, among others, have shown that even Hatteria of the present day is closely related to Lacertilia. Without wishing to repeat the arguments of the authors named, I might only call attention to the great differences between Hatteria on the one hand and Proganosauria and Rhynchosauria on the other. The nearly dogmatized isolation of “Rhynchocephalia” is severely shaken by this. Also, it is not admissible to judge a whole host of fossil reptiles by the present-day Hatteria, for this has recently been claimed, from a zoological point of view, as a highly specialized lacertilian.
PROTEROSAURUS-LIKE REPTILE FROM THE BUNTER SANDSTONE
In the collection of the Geological Institute at Halle is found a large slab from the Cheirotherium Beds of the Middle Bunter Sandstone of Bernburg, which contains a confused jumble of poorly preserved bone remains. The hon. VON FRITSCH called my attention to it very kindly with the comment that it was probably a proterosaurid. This view seems most likely to me although I do not venture to maintain it with absolute certainty. I refer to the interesting occurrence here only for the sake of the completeness of the review of the Triassic.
The elongated caudal vertebrae, the short and high dorsal vertebrae, the femur and the abdominal ribs seem to me to indicate a proterosaurid. Five cervical vertebrae are preserved in connection and two isolated; in a length of ca. 4 cm they reach a height of ca. 2 cm; the zygapophyses are strongly developed, and the spinous process is broad and low. One of the caudal vertebrae recalls the 4th cervical vertebra of Proterosaurus speneri which SEELEY figured (1). The dorsal vertebrae have distally thickened spinous processes. The four connected dorsal vertebrae are 2.5 cm long and 4-5 cm high; the centrum itself is only ca. 1.5 cm high. An upper arch shows a long, thick spinous process, and an articular surface displays a deepened facet. The numerous dorsal ribs are single-headed with a thickened and particularly high proximal end that possesses a trace of doubleness. Angularly curved abdominal ribs of varying structure are scattered over the whole slab; between them lie peculiar structures that I take for cervical ribs. The broad, straight femur is quite reminiscent of Proterosaurus. Pubis and scapula are not unlike many Sauropterygia. It is not my intention to describe this unique find or to name the animal (2). I specify it only as a proterosaurid.
In connection with “Rhynchocephalia” a few words will be said on Ichthyopterygia. In the Triassic they still play quite a subordinate but nevertheless very interesting role, for this later so important group appeared for the first time here. Certainly the Triassic Ichthyosauria do not indicate as much of the phylogeny of that class as one might hope. BAUR first called attention to the fact that radius and ulna in the skeleton from the Raibl beds of Besano, which he separated as Mixosaurus, are still clearly elongated bones and readily distinguishable from the carpals. This was the first confirmation of the natural postulate, that the Ichthyosauria must have come from land reptiles; from which ones is certainly the important question, and we are still unfortunately not certain on this. Tibia and fibula are elongated just like the forearm bones. The main difference, however, from Liassic Ichthyosauria lies in the shoulder girdle (3).
Unfortunately it is still not possible to say anything at present on the phylogeny of Ichthyosauria. The general plan of the head agrees, as Rhynchocephalia. The pineal foramen in both lies in the posterior half of the frontals and not in the parietals as in most Reptilia.
The Ichthyosauria appear for the first tine in the Wellenkalk. They are found particularly frequently in western Württemburg, less often in north Germany (e.g. at Querfurt, north of the Harz). Several of the smaller vertebrae recall Mixosaurus very much; other larger ones certainly differ. It is not impossible that the latter belong to Shastasaurus. Here I reckon particularly an upper arch of a dorsal vertebra from the Wellenkalk of Freudenstadt, which is found in the Tübingen Museum. The spinous processes of Mixosaurus are long and slim but Shastasaurus has thick, short spinous processes with weakly developed zygapophyses, as also the upper arch in question from Freudenstadt. The Tübingen collection possesses from the same locality and stratum a well-preserved episternum, which is far broader than that of a Liassic Ichthyosaurus and itself broader than that of Mixosaurus. The humerus, which E. FRAAS figured in his time (1), and because of which he placed the Swabian species in Mixosaurus, is interpreted incorrectly; according to FRAAS it should possess two articular surfaces separated by an interspace at the distal end, which indicates an elongated radius and ulna. But now the humerus of Mixosaurus has, in spite of the fact that these bones are noticeably elongated, two distal articular surfaces meeting each other roof-like exactly. If one examines the Tübingen humerus, the surface interpreted as an articular facet is doubtfully a fracture surface, while the interspace is a part of the articular surface pushing closely into the other. But a definite conclusion on Mixosaurus or Ichthyosaurus cannot be drawn from this for they are both the same in this point. Several Ichthyosaurus vertebrae have been found also in the Lower Muschelkalk at Halle am Saale, among others a small lower jaw which is very like that of Mixosaurus. Larger Ichthyosaurus vertebrae occur in between in the Schaumkalk of Freiburg am Unstrut (Middle Muschelkalk); four of these are found in the Geological Museum at Halle.
In the collection of the Imperial Geological Institute of Vienna are three Ichthyosaurus vertebrae (?Shastasaurus) from Grossreifling, Styria from the Reifling Limestone. Since the large skeleton which was destroyed by the burning of the monastery Admont comes from the same locality (also because of the handed-down drawing (VON ARTHABER, Beitr. z. Pal. Österr.-Ung., Bd. 10, p. 108)), we can probably assume that this also belonged to an Ichthyosaurus and not a Capitosaurus. The block with a 4-foot long head was found in 1843 by Prof. FRANGER. H. von MEYER, who only knew it from a sketch and oral description, compared it with Ichthyosaurus platyodon (1). At Ettersburg, near Weimar, Ichthyosaurus vertebrae have been found in the Upper Muschelkalk, which are now preserved in the Mineralogical Museum at Jena (2).
The Ichthyosauria from the Raibl Beds of Besano have already been mentioned. Shastasaurus pacificus MERRIAM is found in the Upper Triassic of Shasta County, California, and in the Upper Triassic of Spitzbergen (Shastasaurus polaris and Mixosaurus nordenskjöldi HULKE sp. 1873). In the Rhaetic, Ichthyosaurus remains are frequent; I mention centra from the Swabian bonebed, vertebrae and skeletal bones from the Rhaetic of Autun, France (Rhachitrema pellati SAUVAGE is an upper arch of an ichthyosaur, moreover I. rhaeticus and I. carinatus SVGE. also occur there) and numerous vertebrae from the Rhaetic of Aust Cliff, near Bristol; a giant snout fragment also comes from there (size of I. platyodon and I. trigonodon), preserved in the Bristol Museum. From the Kössen Beds of the Schlemmer Mountains in Achenerthal, H. von MEYER knew of two Ichthyosaurus vertebrae (3).
3. ANOMODONTIA (AND STEGOCEPHALIA)
The order of Anomodontia (= Theromorpha) includes a large number of different forms, some of quite peculiar appearance. Many of them attained considerable size. Beside great specialization is found extreme primitiveness.
Most genera are chiefly based on characters of the skull, and here again the greatest authority on South African Anomodontia, H. G. SEELEY, places the greatest value on the development of the palate. He divides the order (4) into two groups, differing rather from COPE and ZITTEL; the first group, Therosuchia, embraces ZITTELL’s Theriodontia and Pareiasauria, the second, Therochelonia, contains Dicynodontia, and thus R. OWEN’s “Anomodontia”. SEELEY also thinks it probable that Mesosauria (Mesosaurus and Saurosternum), which were placed in “Rhynchocephalia” by ZITTEL, should form a third suborder; in any case, however, Mesosaurus is closely related to Endothidontia, which could rather be brought into relationship with Proganosauria. All Anomodontia (as also Sauropterygia and Chelonia) have only a single pair of temporal fossae, but Palaeohatteria and Rhynchosauria have two. However Proterosaurus, which was placed in Proganosauria by ZITTEL, ought likewise to possess only a single pair of temporal fossae, according to SEELEY’s studies and reconstruction. Only in Galesaurus, a theriodont, is the temporal fossa nearly split in two by a piece of bone reaching in from far in front (?postorbital). Palatal dentition which, already as such, recalls Stegocephalia and Rhynchosauria, is found in Pareiasauria and Endothiodontia. The palate of Theriodontia (Lycosauria, Cynodontia and Gomphodontia) strongly resembles Hatteria by the narrow pterygoid, curved characteristically outward. In front lie broad palatines that run backward and downward into a transverse process (“palato-transversal” SEELEY); between pterygoid and palatine lies an unpaired palatal opening as in Hatteria. In Pareiasauria also the unpaired palatal opening is found far back between pterygoid and palatine. The toothed palatines have a great extent; in the middle in front the vomers, which likewise bear teeth, participate in the formation of the palate; long lateral processes of the pterygoid are connected with the quadrate, the basisphenoid is very short. In the massive skull of Endothiodon the unpaired palatal opening also lies behind the main part of the toothed palatine; the latter do not meet in the midline, the channel is closed only further forward by the toothless vomer. The region of the intermaxilla is marked by a deep pit between the two long canine teeth. I lack more exact information on Tapinocephalus (Dinocephalia), SEELEY says: “Palato-nares placed far forward”. Further information on the palate is hard to determine. From OWEN’s figure of a complete skull, one might think that an unpaired palatal opening lies between the palatines close behind the vomer. The posterior part of the palate is not preserved. As far as can be recognized on R. OWEN’s figure of Gorgonops, the pterygoids are delicately built, narrow bones and are strongly curved outward so that large openings remain free below the orbit. The palatines are likewise narrow and terminate close to the maxillae, they only meet in the posterior part; the narrow vomers follow anteriorly (including probably a narrow process of the palatines), on both sides of which the inner nasal openings lie separate; anteriorly they are not bordered by bone, no intermaxilla appears to be present at all, and so a hard palate roof is not present anterior to the middle. Just as in Gorgonops also, the position of the inner nasal openings is on both sides of the vomers in Deuterosaurus, terminated laterally by palatine and maxilla and anteriorly by the intermaxilla. The whole palate is bony; pterygoid, ectopterygoid [transversal], jugal, maxilla, intermaxilla, vomer, and palatine participate in its formation (presphenoid not preserved). The whole palate is very like that of Nothosauria, as SEELEY correctly emphasized. In Deuterosaurus the palate compares best with Dicynodontia. The short sphenoid is surrounded by the pterygoid, which sends the ectopterygoid far anteriorly, and has a pointed process medially that entirely or nearly reaches the vomer. On both sides of this process and the posterior part of the vomer are found the inner nasal openings, which are bordered laterally by ectopterygoid and palatine; anteriorly the intermaxilla occupies quite a large pit. Ptychognathus, which belongs in this group, differs somewhat in that the nasal openings are only separated by the vomer, and a high bulge surrounds the sides and dorsal wall of the same (pterygoid and ectopterygoid). The palatines recede almost completely.
The palate of Anomodontia can scarcely be compared with Stegocephalia, not even Pareiasaurus, which however recalls this ancient animal group in many parts. But the sculpture of the covering bones of the skull, their dermal plate-like form, the nearly complete roofing over of the temporal fossa; all these are conditions which, are found again very similarly in Cyclotosaurus, Mastodonsaurus, and other Triassic Labyrinthodontia. The small frontals which surround the orbits not at all or only in short stretches, are common to Theriodontia, like e.g. Procolophon, etc., Temnospondyli (e.g., Actinodon) and other Stegocephalia. The supratemporal also in Pareiasaurus and Mastodonsaurus is present in the same way. In Anomodontia all transitions are present from a single occipital condyle to the two-headed one of Stegocephalia, i.e. the so-called amphibian type. The three-part condyle forms the transition step, e.g. Dicynodon. In general no absolutely certain characteristic for the separation of older Amphibia and Reptilia is known to me. Amnion and allantois naturally cannot be considered here, for it is a question of fossils. Who can prove that the differences accepted as sweeping by zoologists in this point are not later acquisitions of one branch of a common stem? It might almost seem as if in reality the great difference held by us between Amphibia and Reptilia did not exist yet then (1).