The Origin of the Idea of the Mammal-Like Reptile

The Origin of the Idea of the

Mammal-likeReptile

RICHARD P. AULIE mammalian evolution. As fossil reptiles which more nearly approximatedthe mammalian condition continued to be discovered,he suggested they would be found to have larger and larger dentary bones, with a corresponding

* Conclusion of a three-part article. In earlier parts the diminution of the other osseous components of the lower Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 author recounted the discovery of the Karroo fossils in jaw. Remarkably, he even attempted to predict the kind South Africa and the controversy surrounding them of articulation in the jaw-joint between mandible and (ABT 36[81:476)and traced the growth of scientific un- cranium that would characterize an intermediate fossil derstanding of the reptile-mammal transition (ABT 36[91:545).He discusses, here, the implicationsfor zoology at the transition between reptile and mammal (Seeley and paleontology today and summarizes with comments 1889: 291, 292). Moreover, he noted, an improved second- on the "model"aspects of the controversyand its resolu- ary palate would be found, which, by separating the nasal tion. References cited in earlier parts are included here, from the mouth cavities, would in mammals increase the as are the author's acknowledgments. ease of breathing and masticating. And by proposing a division of the Karroo strata into stratigraphical zones, he drew attention to the possibility of arranging the fossil Ill. The Mammal-like Reptiles reptiles into chronological sequences (Seeley 1892: 311- 314). These were the kind of problems that emerged from Owen's studies, problems that Owen perhaps only im- perfectly understood. Applications of Evolutionary Theory In 1895, Seeley described several species of a cynodont which, as the most advanced of any then known, seemed to corroboratewhat he had foreseen (Seeley 1895a). Calling FOLLOWING THE PUBLICATION of Darwin's this genus Cynognathus, meaning dog-like jaw, he found Origin of Species, in 1859,biologists were eager to ap- that the dentary comprised almost the entire mandible, ply the theory of evolution to the paleontological with the other bones crowded at the back. Moreover,be- record.In the case of the Karrooreptiles, this was a cause the dentary was very near the squamosal bone of gradual trend which lagged behind other applica- the cranium, the joint rather closely resembled the mam- tions, such as the promptevolutionary interpretation malian condition (fig. 18). Besides having a secondary of the fossil horses. But Owen's pioneer work, his palate, Cynognathus had two occipital condyles, the all- speculations of 1876 and 1880, and the supportgiven important trait, that, as in mammals, provides articula- his views by Cope, inevitably fostered an increasing tion with the backbone. These typical cynodonts, the most confidencethat at least some mammals were derived mammalian-like of the theriodonts, were represented from reptiles rather than from amphibians, and that hitherto mainly by Owen's Galesaurus (and Thrinaxodon). the theory of evolutionwould offer a fruitfulline of in- quiry. As this realizationgrew, the predictivevalue of evolutionarytheory quickly became apparent. Emerging Concensus

Predictive Value New trends in research, the continued accumulation of fossil evidence - much of it circumstantial - and reflection the discussions Even before a concensus had been achieved concerning on Owen's diagnostic methods enlivened of the of mammals during the closing years of the mammalian origins, Seeley in 1889 already foresaw im- origin 19th century. At the 4th International Congressof Zoology portant problems that have, in fact, since been the subject in 1898, paleontologists had in mind a rather clear con- of paleontological research. Three of these have to do with cranial morphology and are central to the question of ception of a long-limbed, quadrupedal, terrestrial, and aquatic reptile, with pronounced-often astounding- mammalian features, which flourished during the Permian The author is in the department of natural science at Loyola University, 820 N. Michigan Ave., Chicago60611. A biographical and Triassic periods. note (with photo) appeared in the first part of this article (ABT But questions remained (Osborn 1898; Osborn et al. 36[8]:476). 1899). Did mammals come from amphibians or reptiles?

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Fig. 18. Cynognathus,figured by Seeley, about 30 cm long. The lateral view has a striking resemblance to a dog; at least Seeley thought so, judging from the name he coined. The mammalian features of this advanced theriodont give us a good idea of the life it led during the lower Triassic. The teeth are specialized into incisors, fangs, or canines, and cusped molars. Notice the sagittal crest, rising just posterior to the eye orbit, for attachment of Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 strong temporal muscles. Cutting, piercing, and chewing of food were assisted by the well-developed secondary palate (unseen here). Unseen also are two occipital condyles, extremely important, in mammals, where the skull swung on the vertebralcolumn. Undoubtedly this creature was very predaceous, an active and powerfulcarnivore. (Seeley 1895a: 72.)

If the latter, which ones? Were these Karroo reptiles ancestors of monotremes only, or of all the mammals? Although Huxley's view still persisted, Seeley's summary Fig. 19. RobertBroom, South African vertebrate paleontologist, of the conflicting evidence made plain that the questions physician, and student of mammalian evolution. Born, Paisley, could not yet be settled. After ten years' hard labor, Seeley Scotland, Nov. 30, 1866; died, Pretoria, South Africa, April 6, 1951. Educated in medicine at the University of Glasgow, he was puzzled. Perhaps those mammalian traits he had con- emigrated in 1897 to South Africa, following his recognition of firmed in the Karroo reptiles were due only to parallelism. the importanceof the Karrooreptiles for the study of mammalian He suggested that a "common parent" for mammals and evolution. He taught geology and zoology in 1903-10 at what is anomodonts (including the theriodonts) might be found in now Stellenbosch University, near Cape Town, and from 1934 rocks even older than the Permian (Seeley, in Osborn, served as curator of paleontology at EransvaalMuseum in Pre- toria. He is most famous for his contributions to physical anthro- H., et al. 1899: 68-70). pology by his studies of prehistoric man in Africa, and for his Meanwhile, the rapidly increasing supply of fossil speci- discovery in Pleistocene deposits of the Australopithecines, mens had made reforms in nomenclature imperative. In Plesianthropus transvaalensis at Sterkfontein in 1936, Paran- 1903, Henry Fairfield Osborn (1857-1935), vertebrate thropus robustus at Kromdrai in 1938, and Paranthropus cras- paleontologist at the American Museum of Natural His- sidens at Swartkrans in 1948. But most extensive were his studies, beginning in 1897, of the mammal-like reptiles. He made tory in New York City, drew attention to the temporal important visits to the U. S. in 1909, 1913-14, and 1928, and he fenestrae which Owen had noticed in 1845 in Dicynodon. came for lectures in 1937 and 1949. Among other honors, Broom Accordingly, Osborn classified the Karroo reptiles as was awarded the Daniel Giraud Elliot Gold Medal of the U. S. "synapsids" because they have in common a single zygo- National Academy of Sciences in 1950 in honorof his work on the matic arch (cheekbone) bordering this region, which thus Australopithecinae.Among other books (see references), he wrote The Origin of Man - Was It Accident or Design? (1933) and Find- separates them from the "diapsids" (two-arched), which, ing the Missing Link (1950). With firm, religious convictions, Osborn thought, contained all other reptiles. And he was Broomsought to interpret evolution as an expression of a cosmic, perhaps the first, the same year, to use the term "mammal- divine plan. Courtesy of the American Museum of Natural His- like reptile" (Osborn, H., 1903: 453). tory, New York, where he posed with Endothiodon uniseries At least with respect to interpreting the Karroo reptiles, (Owen 1879b) for this picture during his visit in 1913-14. the break with idealistic morphology was now practically complete. The mammal-like reptiles, as the term implies, mens available was limited and the literature manageable, were henceforth explained somehow by the theory of Seeley could master all that was then known. But when evolution: homologies suggested a common ancestry, at the turn of the century the mammal-like reptiles were rather than empirical expressions of a transcendental placed in an evolutionary context, the flood-gates seemed eidos (Idea). As a unifying principle, the theory of evolu- to open. During the next three decades, newly-discovered tion since 1900 has given meaning and coherence to an fossils of primitive, specialized, and advanced forms flowed otherwise bewildering mass of observations. The 19th- steadily from the Karroo beds. Paleontologists of several century work, represented by Bain's initial discovery, nationalities took up highly theoretical and recondite Owen's foundation studies during a 42-year span, and problems, many of them extensions of those Seeley had Seeley's elaborate memoirs, were for the most part de- foreseen. The result was for some years an almost ex- scriptive and exploratory. Because the number of speci- ponential increase of the literature.

22 THE AMERICAN BIOLOGY TEACHER,JANUARY 1975 The Leadership of Robert Broom specialists, such as David Meredith Seares Watson (1866- 1973), to the subject (fig. 19). Following his graduation from the University of Glas- The study of the Karroo reptiles was an international gow medical school in 1889, Broom went to Australia, endeavor from the start-when Bain sent his first collec- where he hoped the most primitive living mammals would tion to the Geological Society of London. It became de- provide clues to the origin of mammals. But he saw the cidedly so at the beginning of the 20th century, when direction his life would take during a visit to London in in in specialized workers increased number major mu- 1896, when he became further acquainted with Seeley's seums and universities on every continent. But to a large work and had an opportunity to examine his collection of extent, the term "mammal-likereptile" must be associated cynodonts. Realizing at once that the Karroo reptiles with Robert Broom (1866-1951), whose great work looms would hold the evolutionary key to the origin of mammals, large over all that has been discovered about this group and with the resolution he displayed throughout his life, of reptiles, and whose inspiration quickly drew other Broom and his wife emigrated without hesitation to South Africa in 1897, there to assemble the fossil evidence required for the solution of the problem.

In South Africa Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021

Broom soon challenged Seeley's reign over the Karroo reptiles. Broom was the first to map out the main paths of evolutionary change, as recognized today, which led from reptiles to mammals. By earning a modest livelihood as a doctor, often in remote communities, and sometimes as a teacher, he financed his own fossil-collecting expeditions on which he excavated an astonishing array ofjaws, teeth, skulls, and skeletons from the sedimentary layers that are found in the Karroo basin of South Africa. Working as a "loner," Broom focused his energies on many classic morphological problems presented by these specimens U (skull structure and the homologies of the cranial bones, the palate, jaw-bones, dental succession, auditory ap- paratus), often interpreting them accordingto the anatomy and embryology of extant mammals. Thus he learned to use fossil evidence to solve problems in comparative anatomy that arose in studying living mammals. A basic requirement in Broom's successful deployment of his fossil evidence was to know the chronological sequence of the strata in which he found his specimens. In 1905 he identified separate faunal zones in a section of the Karroo strata, called the Beaufort series, which Bain had described in more general terms in 1856. Extending upward from the mid-Permian to the mid-Triassic, the Beaufort represents approximately 40 million years of Fig. 20. The remarkable variety of South African therapsids is fresh-water and wind-blownsedimentation. Its zones were shown by these skull specimens of three genera belonging to as named after the predominant genus that had been de- many suborders,all from the middle and upper Permian period. scribed either by Owen, Seeley, or himself: Tapinocephalus (Top) Dorsal and lateral views of a carnivorousGorgonops (Owen at the bottom, then, proceeding upward, Endothiodon, 1876c), a theriodont, about 20 cm long, with flattened temporal region, and long and heavy snout. (Bottom left) The skull of the and Cistecephalus,in the Permian; and in the Triassic, the largest known anomodont, Platycyclops (Broom 1932), has an Lystrosaurus, Procolophon, and, as the most recent, Cynog- astonishing length of about 75 cm. Dorsal view shows a prominent nathus at the top (Broom 1905a; Kitching 1970). This pineal foramen in the center. It is related to the herbivorous scheme allowed him to identify specimens according to Dicynodon (fig. 3) and Aulacocephalodon (fig. 22). (Bottom right) particular time intervals, to estimate the longevity of The skull of this Therocephalian, Whaitsia (a primitive carni- vore), about 18 cm long, shows a curious open structure. Note the genera, and to work out, with morphological data, their very large temporal fenestrae that face dorsally, and come in phylogenetic relationships. The strata proved to be an toward the midline. First named by Broom (1932) for the South extraordinarily rich source of fossil materials (fig. 20). By African collector, Rev. John W. Whaits, this form paralleled his own field work, and by describing and bringing to light Gorgonops,and gave rise to the more advanced Bauria (fig. 21). the collected by other fossil-hunters, such as (See Romer 1968a.) These three forms illustrate the parallel specimens trends, towardthe mammaliancondition, which Broomdescribed. the teacher and postmaster Alfred Brown (ca. 1834-1920) Courtesy of Bernard Price Institute of PalaeontologicalResearch, and the Rev. John W. Whaits (1870-1947), Broom inevit- Johannesburg. ably multiplied the number of known species.

ORIGIN OF THE IDEA OF THE MAMMAL-LIKEREPTILE 23 Major Contributions

Reporting his findings in a torrent of about 290 publications from 1897 to 1932 (about 456 publications in his life), Broom made three major contributions to the study of the origin of mammals. In the early years of his career, he first of all marshalled strong evidence before the scientific community that mammals had evolved from a mammal- like reptile, probably a cynodont or one of its derivatives (Broom 1905b; Broom 1907). He proposed the designation "therapsid" for the major synapsid suborders of mammal- like reptiles (which he called the Anomodontia, Cyno- dontia, Dinocephalia, and Therocephalia) (Broom 1903). Fig. 21. (Top) Bauria cynops, figured by Broom. Sharp incisors, In 1909, during a short visit to the American Museum of piercing canines, peg-like molars, and snapping jaws formed the intimidating armament of this curious and undoubtedly auda- Natural History in New York to study Texas Permian cious reptile, which was almost a mammal but not quite. Skull, reptiles as a guest of Osborn, Broom agreed that therapsids about 13 cm long, shows significant advances toward the mam- came from pelycosaurs, as Cope had suggested, and also malian condition, paralleling those in cynodonts.These advances concluded that the South African therapsids were there- are (i) slender zygomatic arch (cheekbone);(ii) upright coronoid Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 fore descendants of immigrants which crossed a land process of mandible (but with postdentary bones in place); (iii) incomplete post-orbital bar, leaving a kind of sharp spur; (iv) bridge from the Americas during lower Permian times widening of temporal regions (top view); and (v) dental differen- (Broom 1910b). Thus Broom soon laid to rest Huxley's tiation. Eschewing the use of photographs,Broom with great skill hypothesis and Seeley's doubts. Broom's reptuation as a drew his own diagram, often showing restorations from several vertebrate paleontologist was assured when in 1913 he imperfect specimens. He has successfully capturedhere the mosaic expounded his views in the Croonian lecture, "On the of mammalian and reptilian features of this impressive character of the late Permian. From Broom (1932). (Bottom) Diagrams of Origin of Mammals," before the Royal Society of London Bauria, showing details of bones of the cranium and mandible in (Broom 1915a). He summarized his views in a short book dorsal and lateral views. Abbreviations same as in fig. 12. Cour- for students, in 1930. tesy, Bernard Price Institute of Palaeontological Research, When South African government authorities seemed Johannesburg. uninterested in his work, Broom's friendship with Osborn pmx prompted him in 1911-13 to ship a collection of 100 speci- sis srn f Po mens to the American Museum of Natural History in New York (Broom 1932: 309; Gregory 1948). During a short mx~~~~~~r visit there in 1913, he prepared these materials for public exhibition, including the mounting of four complete anomodont skeletons, such as Endothiodon uniseries (Broom 19). Broom's gesture, while it 1915b; Owen 1879b) (fig. eo ept e was viewed with appreciation abroad, was now met with P sq pro disapproval at home. Bain, on the other hand, had shipped case after case of specimens out of the country to England without attracting attention. The protest indicated that the mammal-like reptiles had suddenly become a valuable Broom showed how mammal-like reptiles rose, declined, national asset. and were replaced in an overlapping sequence. For exam- With massive evidence at his disposal, Broom set forth ple, the hardy, though sluggish Dicynodon, with crowds of his two other major contributions to the subject. In his genera, about 90 of them, flourished for 20 million years many published papers, he showed that sequential changes before suffering extinction at the close of the Permian in morphology had occurred among these terrestrial, (fig. 22). In the early Triassic their places were taken over aquatic, and semiaquatic tetrapods in the direction of by the related anomodonts, such as the Lystrosaurus fauna mammals (fig. 21). That is, during 40 million years from (fig. 24) and Kannemeyeria. Similarly, the primitive gor- the Tapinocephalus to the Cynognathus zones of the gonopsians (Owen 1876c) and most of the therocephalians Permian-Triassic, the therapsids became increasingly and their descendants also perished in the Permian, often mammal-like, particularly with respect to changes in with the disappearance of those on which they preyed skull structure (such as the secondary palate, cranial (fig. 20 and 21) (Kitching 1970). And in the Triassic, the bones, occipital condyles, the sella turcica which houses cynodonts then rose to prominence (fig. 15-18). Broom the pituitary gland, and mandible) and also in various described two of the most mammal-like skulls of all in a post-cranial features involving changes in posture. More- layer above the Cynognathus zone. Calling them Ictido- over, he showed that the mammal-like reptiles could not sauria (in 1929), he thought they came from cynodonts be arranged in a single, direct sequence from pelycosaurs and that they probably were the source of mammals. (The to mammals but that these morphological changes repre- details of Broom's contributions are ably summarized in sented a parallel and branching trend. Mammalian traits the commemorative volume edited by Du Toit (1948); by therefore were acquired independently in a number of Watson (1952); and by Gregory (1951, vol. 1, ch. 16), which different groups (fig. 20). also summarizes advances on Broom's work.)

24 THE AMERICAN BIOLOGY TEACHER,JANUARY 1975 In 1932, assisted by the Carnegie Corporationof New in the reptilian jaw-joint was replaced by a dentary- York during the depths of the worldwideeconomic depres- squamosal articulation, a feature that distinguishes the sion, Broompublished The Mammal-LikeReptiles of South mammalian skull. Africa and the Origin of Mammals, his definitive work on Few problems have engaged more serious attention by the therapsids. These were "the most important fossil comparative anatomists, embryologists, and paleontolo- animals ever discovered,"he declared (p. 1). In addition gists during the last hundred years than the homologies to summarizing his multitude of research reports, he de- of the mammalian ear bones. With respect to the inter- scribed 422 species in 282 genera and four orders;of these, pretation that has emerged, several points may be incredibly, were about 277 species that he had established advanced: the conclusions outlined above were first himself. (After 1932 he described many more species.) His proposed on the basis of embryological data, with no as- book represents a quantum jump in knowledge of the sub- sistance from paleontology. Indeed, embryological evi- ject since the publication of Owen's Catalogue in 1876. dence has often led to predictions concerning fossil forms (A further quantum jump is represented by Watson and not then known, but which have since been described. Romer [1956].) Subsequent findings in paleontology were entirely con- Broom apparently never disavowed the early influence sistent with these conclusions. And recent discoveries in he had received in the Plymouth Brethren and Congrega- paleontology have fulfilled rather precise predictions tional Churches in Scotland. With an unusual knowledge concerning the evolution of the jaw-joint of mammal-like

of the Bible, he occasionally spoke before church gather- reptiles. Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 ings and viewed evolution as the working out of a divine The idea that the mammalian auditory ossicles are purpose (Dart 1951: 4). He thought that natural selection homologous with reptilian jaw bones was actually pre- could not have been the chief mechanism of evolution, but Darwinian in origin. It was stated in 1837 by Karo that "some intelligent controlling power has specially Bogislaus Reichert (1811-83), a German anatomist who guided one line to result in man" (Broom 1932: 333; also, studied the ontogenesis of the visceral arches of verte- Broom 1930: 145-150). This position should not be attrib- brates. During the remainder of the 19th century, "Reich- uted entirely to his firm, religious convictions but also to ert's theory" was strengthened by new evidence from the fact that he did most of his work before the genetic comparative anatomy, such as the similarity in shape of explanation of Darwin's theory of natural selection had the malleus-incus and articular-quadratejoints (Goodrich been generally accepted.Moreover, Broom greatly admired 1958, vol. 1, ch. 8, "Middle Ear and Ear Ossicles"). This Owen, and considered himself Owen's successor, as, in- problem was heatedly debated at the turn of the 20th deed, he was in many ways. century. Some anatomists complained that hearing and A forceful and lively personality, Broom invested the chewing could not have occurredat the same time during concept of the mammal-like reptile with the more than these architectural refurbishings, particularly when the three decades of scholarship that made it central to under- quadrate was changing into the incus, or that the stapes standing the theory of evolution (Findlay 1972; Le Gros could not possibly be in contact with the quadrate. Clark 1951). For a time, Broom doubted Reichert's view, but in 1912 he agreed that the quadrate is homologouswith the incus. He then turned to the problem of explaining the evolu- An Active Research Front tionary events that might have occurred (fig. 23). In describing Cynognathus, an advanced cynodont, Broom The concept of the mammal-like reptile, as originally (1912: 423-425) declared: outlined by Owen, continues to provide the matrix for specialized studies along the lines that were more fully The slippingout of the quadratefrom the joint is not elaborated by Broom. In the voluminous literature since nowa very seriousdifficulty, for in Cynognathuswe see 1900 one can follow the treatment of classic morphological it alreadypartly slipped out. Noris thereany verygreat seriousdifficulty in understandinghow the newdentary- problems, sufficient to whet the appetite of any serious squamosaljoint arose. In Cynognathus,the posteriorend biology student. These problems often show how develop- of the dentarynearly takes part in thejoint, and there is ing concepts of anatomy, embryology, and paleontology no difficultyin realizingthe next stagein the evolution, frequently coalesce in the formation of ideas that are now wherethe dentaryand articulartogether hinged on the almost commonplacein biology. squamosaland quadrate. As the directarticulation of the dentaryand squamosal became more firmly established, the quadrate,articular, and angulardegenerated, and The Jaw-Ear Complex might have been lost had not the attachmentof the stapes to the quadratecompelled them to take on an auditoryfunction. One of these ideas is the evolutionary origin of the three bones of the mammalian middle ear: the malleus (ham- What is significant in this passage is that Broom made a mer), incus (anvil), and stapes (stirrup). Accordingto this prediction (also in Broom 1932: 325, 326) that can be interpretation, the malleus is derived from the articular expected in evolutionary theory but not in the doctrine of bone (with the goniale) of the reptilian mandible, the incus special creation. He forecast the kind of fossil that would from the quadrate, which is lodged in the reptilian cran- characterize the mid-point between reptile and mammal ium, and the stapes from the columella auris, which in with respect to the jaw-joint. The hinge would have two reptiles extends from the ear drum to the fenestra ovalis. bones on each side-"the dentary and articular .. . on the In the transformation, the articular-quadratearticulation squamosal and the quadrate."

ORIGIN OF THE IDEA OF THE MAMMAL-LIKEREPTILE 25 Paleontological research by Broom and many other parallel therapsid lineages, with several branches ap- workers has gone far toward substantiating with empirical proaching the mammalian grade. evidence the otherwise hypothetical conditions repre- 2. Single or multiple origin of mammals. Do these multi- sented by Reichert's embryological theory. Examples of ple lineages mean that mammals had a multiple origin? trends toward the mammalian condition are (i) resem- Or was the threshold crossed only once? Certainly a num- blances between the post-dentary and quadrate bones of ber of forms, including tritylodonts, ictidosaurs, and cynodonts and the mammalian ear ossicles; (ii) reduction bauriamorphs, were almost mammals in the late Triassic. in size of post-dentary and quadrate bones; (iii) that in If the descendants of more than one of them made it across some fossils, the reduced quadrate has become free-float- the line, then mammals had a "polyphyletic" origin. ing, with no sutured or ossified boundaries with its neigh- Widely held for many years, this theory was further ex- bors; and (iv) that in cynodonts the columella auris touches plored by Olson in an ingenious and comprehensive in- the quadrate, so that the articular, quadrate, and colu- vestigation of cranial cross-sections of four therapsid mella auris form a line of contiguous bones, as do the suborders (Anomodontia, Cynodontia, Gorgonopsia, and three mammalian auditory ossicles (Gregory 1913; Olson Therocephalia), in order to compare the ear complex, 1944; Parrington 1955). occipital region, and basi-cranial axis of each. He con- Even more remarkable was the description of a fossil cluded that "mammals originated not from one stock of which, with respect to the jaw-joint, is almost exactly on therapsids but from several" (Olson 1944: 124).

the threshold between reptiles and mammals. The fossil On the other hand, development of entirely new evi- Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 was one of Broom's ictidosaurians (Broom 1932: 302), one dence concerning dental characters-molar cusp patterns, that A. W. Crompton in 1958 renamed Diarthrognathus tooth replacement, differentiation of postcanines-of re- broomi, when his careful examination showed that its jaw cently discovered Triassic mammals (Morganucodontidae swung on both dentary-squamosal and articular-quadrate from British sediments) has convinced Hopson and contacts. This creature was therefore either a highly Crompton (1969) that a "monophyletic" origin is more advanced therapsid, although perhaps not a cynodont, or likely. They conclude that the parallel trend is more a Triassic mammal, depending on the trait that is arbi- limited than the literature implies and that the mam- trarily chosen as diagnostic. Crompton's finding is a re- malian threshold was crossed only once, probably by markable fulfillment of Broom's prediction (and that of "persisting members of the Family Galesauridae" (p. 68). Parrington [1949: 590]) that the transitional form of the According to Barghusen (1968), a monophyletic origin is jaw would have two bones on either side of the joint. It also suggested by the probable similarity of the jaw has been suggested that this double-jaw articulation might musculature of cynodonts and mammals. have occurred in several different forms (Barghusen and 3. What is a mammal? These discussions in the litera- Hopson 1970). Very likely in such forms audition occurred ture have kept alive rather basic questions of classifica- with suspension but without evidence of an ear-drum, tion. Of course, biology today has quite workable criteria which is so far lacking; we cannot be sure that both func- for placing living mammals in one taxon and living reptiles tions were combined in such a double-jaw articulation. in another; for a start: soft anatomy, activity, and temper- Hopson (1966) has described the probable functional ature control. But we cannot dismiss the osteological and changes in the components of the jaw-joint during the dental characters among the mammal-like reptiles. If transformation of the articular and quadrate bones into these characters indicate a former continuity between the malleus and incus. reptiles and mammals, what, then, is the difference between the two classes? This question is still worth ex- amining in the light of the paleontological data. It was the Recent Research subject of a fascinating exchange of views in Evolution,

1. Independent acquisition. Another challenging problem now receiving attention in the literature is the independent acquisition of mammalian traits by diverse therapsid lines, the parallel trend that Broom abundantly charted (fig. 20 and 21). How was it possible that several groups of herbivores and carnivores (anomodonts and theriodonts) during the Permian-Triassic, though of different taxonomic ranks, could become more and more mammal-like? They did so in the presence of other highly variable groups of reptiles, apparently under the same Fig. 22. Aulacocephalodon peavoti, about 2.5 m long. Complete environmental conditions and during the same periods of skeletons of therapsids are rare. Classified with Dicynodon, this time (Olson 1959; Simpson 1964: 166-169). once heavy-set, clumsy, and slow-moving fellow is now on exhibit Do these multiple lines represent the gradual, pheno- at Field Museum of Natural History in Chicago. Although it has typical expression of a shared genotype that was inherited mammalian resemblances, it left no descendants that crossed the from the pelycosaurs? What causal agencies might have mammalian threshold. Its toothless jaws suggest a diet of plants, which perhaps were found in swampy regions. No doubt it was been at work? Perhaps there is no answer. But the con- preyed upon by more agile flesh-eaters. Compare rib cage with tinuity between pelycosaurs and mammals seems con- that shown in fig. 17. Courtesy, Field Museum of Natural His- ceptually clear. Directional evolution characterized the tory, Chicago.

26 THE AMERICAN BIOLOGY TEACHER,JANUARY 1975 4. Gondwanaland. The Karroo reptiles have contributed to a clearer picture of what the world was like during Permian-Triassic times, as their relatives have now been found on every continent. Indeed, the term "Karroo reptile" may have become a misnomer as early as 1876 when Owen described a similar specimen from Nova Scotia (fig. 6). In recent years, the widespread occurrence of therapsid fauna A B outside South Africa has provided striking confirmation for an idea that occurred to the botanist Sir Joseph Dalton Hooker (1817-1911) during an expedition to the south seas in 1839-43. (Owen may have surmised the same Art.Art idea. See quote in part 2 from 1880: 423.) In his Flora Novae Zelandiae (1853, "Introductory Essay," p. xxi), Hooker probed the inability of the doctrine of special creation to account for the discontinuous distribution of plants. Reflecting on the recurrence of familiar plants on widely separated spots of land in the south seas, he

speculated on the possibility that the related, insular Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 D.. flora, including that of Antarctica, Australia, Chile, New Zealand, and Tasmania, might be the stranded descendants of flora that once had a continuous range over a great southern landmass. Hooker's idea of a landmass became the hypothetical Paleozoic supercontinent Gondwanaland. Nourished by geological evidence, the associated concepts of rifting and continental drift are now widely accepted as explanations for the present land regions of the southern latitudes (Du Toit 1939). (But G. W. Bain [1964] questions the evidence for continental drift, and argues instead that large chunks of Gondwanaland foundered, leaving the present ocean basins and continents in place.) How, then, did dicynodons get to South America and to the western United States? E F Did they trek overland via the Bering Straits and Panama from China, where they also thrived? Very likely they did not. The dramatic discovery in 1969-71 of Lystrosaurus Fig. 23. Prediction of a double-jaw articulation. In these dia- (fig. 24) and Thrinaxodon (fig. 16 and 17) in Antarctica grams Broom in 1912 showed possible steps in the evolution of (in strata similar in texture to those in South Africa) has the mammalian jaw-ear complex. Abbreviations:art., articular; pof f ang., angular; sq., squamosal; qu., quadrate; st., stapes. Articula- tion of the mandible with the cranium changes in each stage. A, Dicynodon; B, Cynognathus, with dentary just visible above prf I n~~~~~~~~~~~~~~~~~~~~~~~~~~~~r articular. Of particular interest is C, where, in this hypothetic stage, he shows the dentary and articular on the mandibularside of the joint swinging against the squamosal and quadrate. This ept double-jaw articulation was described in 1958 by Crompton in Diarthrognathus, a fulfillment of Broom's prediction. D, E, are art hypothetic steps to F, the mammalian condition, where the audi- sq ~~~~~~~~~ret.lamd tory ossicles are functioning in place. Note how the angular X'P (tympanic), articular, and quadrate shift position, and also that Si) the articular, quadrate, and stapes (later the malleus, incus, and stapes) are always in contact. From Broom(1912). Fig. 24. Lystrosaurus mur- rayin, Huxley. Top and side wflere the intriguing suggestion was proposed, and chal- views of cranium, about 12 cm long. This lenged, that mammalian boundaries be extended down- bizarre creature was a semiquatic ward to include the therapsids (Van Valen 1960; Reed relative of Dicynodon. Mem- 1960; Simpson 1960). bers of this genus flourished That the question can be raised at all, and with such during the Triassic in South Africs. They have been an earnest answer, emphasizes that there is indeed a con- found also near the South tinuity between reptiles and mammals. We are also re- Pole, and in China and In- I minded that the means of diagnosing the transition dia. For abbreviations, see between reptiles and mammals is at best convenient and fig. 12. Courtesy of Bernard Price Institute of Palaeontol- arbitrary-perhaps that dentary-squamosal articulation ogical Research, Johannes- for the mammal is at present an irreducible minimum. burg.

ORIGIN OF THE IDEA OF THE MAMMAL-LIKEREPTILE 27 required a further look at well-established ideas of migra- time (Brink 1956; Romer 1968b, ch. 14, "Mammal-Like tion. (For an account of these discoveries, see Colbert Reptiles";also the four examples under "RecentResearch" 1972a, b; Colbert 1973.) These creatures could not have above). swum across the intervening seas, nor is it likely that they could have walked across a narrow isthmus. (Contrasting How the Idea Was Accepted overland migration routes are suggested by G. W. Bain and Colbert.) We may speculate more realistically that therapsids once roamed at will over the vast regions of the We may also analyze the information network by which the earth's surface that once comprised the landmass called the new interpretation gained allegiance within Gondwanaland. Thus, the concept of the mammal-like scientific community. Besides the more traditional pub- reptile promotes a revolutionary concept in geology. lication of research papers, there was informal communication among specialists by correspondenceand consultation and open scientific meetings where ideas could be subjected to scrutiny among peers. It all began, of course, IV. A Model of Scientific Growth when Bain had the courage to write an informal letter (1844) to the prestigious Geological Society of London, which became the initial forum where the new informa- How the Idea Grew tion became known. Of special significance, we may also note the correspondencebetween Bain and Owen and be- Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 tween Broom and Osborn; Broom's consultation with 'WECAN IDENTIFY three stages in the development of Seeley in 1896; the 4th International Congress of Zoology the idea of the mammal-like reptile. To a significant in 1898; Broom'sCroonian lecture of 1913 before the Royal degree, its origin and growth provide a "model"for under- Society of London;and Broom'svisit to New Yorkin 1913- standing how scientific ideas in general gradually encom- 14. By these formal and informal paths of publications, pass a body of knowledge. These stages may be designated correspondence, consultations, and meetings, the evo- according to their predominant leaders: slow, linear lutionary significance of the Karroo reptiles was gradu- growth-Owen; consolidation-Seeley; and exponential ally diffused and accepted-all within the scientific growth-Broom. During this development, significant community. changes in procedure, personnel, and problems occurred The model proposed here can be tested quantitatively within the scientific community.These stages and changes with the bibliography Broom (1932) compiled for the were not recognized by the participants, for we discern period 1844-1932, for which he listed 29 workers and 309 them only in retrospect. This model illustrates how a sci- publications. A useful and simple method is to count the entific idea is born, diffused, tested, accepted, and applied number of publications for five-year intervals. This is an within the scientific community. inexact procedure,for the articles vary in size and signifi- The first stage began when Bain discovered an anomaly cance, and there is overlap. (For example, Broomin 1901- in nature-an observation that does not fit the received 05 turned out 45 articles, but some are only two pages interpretation. With a thorough grasp of what reptiles long; Seelev's of 1895 ran to 89 folio pages; Seeley began should look like, he coined the term "bidental"because he his work in Owen's final years, and Broom began when saw at once that "tusks" in a reptile required a new ex- Seeley was still active.) Yet the procedure is instructive, planation. Then followed a period of random fact-gather- for when plotted against time, we find components of an ing, many more anomalies coming to light, the routine ordinary growth curve, which in fact often describes the organizing of these facts by Owen in formal research development of a scientific idea (Price 1962). In 1845-80, reports, and his selection of useful diagnostic traits. Even- there were 33 publications, most of them Owen's;in 1880- tually, Owen proposed the novel interpretation of evolu- 95, 33 articles, indicating a doubling-time; and in 1895- tion (a "paradigm"),and a few more workers took notice 1915, in 20 years, 154 articles appeared. These data ap- when reading the literature and attending scientific proximate the long period of about 40-45 years of slow, meetings. linear growth, guided by Owen's foundation work; con- The pace quickened during the stage of consolidation. solidation of about 15 years under Seeley; and of expo- Seeley reviewed the literature, made his own collections, nential growth when the theory of evolution was applied further explored the possibility of an evolutionary inter- under the leadership of Broom (and Watson). pretation, and marked out particular problems, which in turn attracted other workers, chief among whom was Broom. The third stage was exponential, because under Why the Idea Was Accepted Broom's leadership the theory of evolution rapidly provided a conceptual view for the anomalous observations, Given the stages of development, the paths of communi- workers became more specialized, they gathered in clus- cation, and the quantitative test of the model, why did the ters for problem-solving,and the research front expanded scientific community accept the evolutionary interpre- as still more problems emerged. Moreover, there was an tation? Because the fossils by themselves indicate that increasing conviction that these problems could be solved evolution has occurred?No, indeed. As we have seen, the within the new interpretive mix of theory and practice, application of the theory of evolution was a long and com- and there was an increasing ability, which continues to plex process. Because leaders in the scientific community the present, to choose significant problems at the right were in league to dictate an "establishment"policy of evo-

28 THE AMERICAN BIOLOGY TEACHER,JANUARY 1975 lution? Hardly. Scientists-in any science-are highly early Mesozoic, with the implication that there was no independent, even while recognizing the importance of distinct boundary anywhere on the evolutionary con- informal communication. They regard the results of their tinuum between these groups of extinct vertebrates. own work, particularly publications, as personal property. The Karroo reptiles remind us that in modern biology Often they find that it behoves them to be prudent about ancient ideas are both preserved and transformed. We sharing discoveries in advance of publication, lest some- say that living reptiles and mammals are separate groups one else take the credit. Concern for reputation and com- in nature, and that a series of transition forms once united petition for priority always prevent conspiracy in theory them. So we perceive these two categories in nature- formation. groups and continuity-as did the ancients. But these Two criteria of acceptability should be noted: the de- categories have been transformed. The groups no longer gree of fit between the theory of evolution and the empir- are earthly replicas of Plato's eternal Ideas. And the tran- ical data and the heuristic value of the theory. The first sition forms no longer are fixed links in Aristotle's scale criterion was applied during the stages of slow growth and of nature. consolidation, and the second during the stage of expo- If an evolutionary continuum means that, at least in nential growth. the past, the two classes, Reptilia and Mammalia, were The theory of evolution became attractive and won not clearly defined in nature, then we may ask whether within the scientific community when its the two living classes do not exist as much in human acceptance Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 members, acting independently, agreed that it would thought as they do in nature. Are they, after all, only most adequately explain the data and that it would render invented categories of the mind, with no objective exist- the science involved more dynamic and fertile. During ence? Perhaps this is what Linnaeus meant when he used this selection process, the ordinary research procedures the aphorism, "Classification is the work of science, spe- required for problem-solving, as outlined above, insured cies the work of nature" (Classis et ordo est sapientiae, that weak arguments were eliminated, false leads identi- Species naturae est; quoted by Owen [1860b: 532]). fied, and hazy issues clarified (forexample, the question of When we say that an evolutionary continuity joins the amphibian origins, identifying quadrate and tympanic reptiles and mammals, we need not say, as did some 18th- bones, and distinguishing between sutures and fractures). century biologists, that nature is a seamless garment, in The result was a gradually widening concensus, first dur- which even species lose their identity. We only say that ing the last two decades of the 19th century, that the the latter group sprang from the former. Long in develop- Karroo reptiles could be viewed as mammal-like reptiles; ment, the idea of the mammal-like reptile emerged along later, that this concept implies that mammals came from the channel opened by Owen, with the interpretation he reptiles, not amphibians; and, later yet, that the concept proposed,and by the diagnostic techniques he pioneered. would have useful implications beyond paleontology, as demonstrated in geology. As Kuhn has remarked recently Acknowledgments.-I am deeply grateful to the staffs of the (1970: 176): "A paradigm is what the members of a scien- following educationalinstitutions in the Republicof South Africa, tific community share, and, conversely, a scientific com- who, in correspondence,graciously answered numerous queries, munity consists of men who share a paradigm." and generously supplied documents and pictures: the Bernard Price Institute for Palaeontological Research of the University of the Witwatersrand,and City Library,Johannesburg; the Library Epilogue of the University of Cape Town;National Museum, Bloemfontein; and Transvaal Museum, Pretoria. Many thanks are also due the When Bain, that resourceful roadbuilder in South Af- library staff of the Field Museum of Natural History, Chicago,for he set in readily providing source materials during the summer and fall of rica, discovered his first "bidental" in 1838, 1973 when this study was done. Many pictures were preparedby motion a lively and protractedenterprise in paleontology. Constancia De La Cruz and Louis Szekeres of the John Crerar Chief among the morphological problems suggested by Library,Chicago, whose library staff, as always, most kindly also his fossils was the bearing the origin of mammals had on provided rare books. Farish A. Jenkins, Jr., of the Museum of the connections among the vertebrate classes. We Comparative Zoology, Harvard University, was kind enough to past loan me the original art work for his Thrinaxodonreconstruction. see in the developments that followed how paleontology I profitedgreatly from conversations with HerbertR. Barghusen, interacted with changing interpretations of organic na- University of Illinois Medical Center, Chicago; and James A. ture, and how diverse segments of the scientific commun- Hopson, Department of Anatomy, University of Chicago, who ity contributed to the idea of the mammal-like reptile. showed me a cast of the rare Tritylodon;and fromcorrespondence with George W. Bain, who wrote to me about Gondwanaland; This enterprise gives us the occasion to ask important Leonard Broom, who wrote to me about his father's career; and questions about how concepts in biology develop, and bids James W. Kitching, of the Bernard Price Institute for Palaeonto- us reflect as well on those issues that transcend biology. logical Research, who contributed the splendid photographs of The Karrooreptiles exist in the geologic strata and, now therapsid skulls. John Bolt showed me the Dicynodon collection shelves. The "mammal- at the Field Museum. Gil Stucker, of the American Museum of in their multitudes, on museum Natural History in New York City, gave me access to the Broom like reptile" existed first in the minds of the paleontolo- collection, which includes examples of most of the specimens gists who studied these fossils. As an invented idea, it is a discussed here, and to the Broom correspondence.The manu- mosaic of reptilian and mammalian traits, representing script was read in full or in part by James A. Hopson;James W. and George D. Morgan,Professor Emeritus of Biology, a continuity which once prevailed between K;tching; morphological Denison University. They all rescued me from needless blunders the two classes, Reptilia and Mammalia. More precisely, in vertebrate osteology, offered usefullcomments, and patiently it represents a chronological continuity between the answered questions. And I also much appreciate the enoourage- pelycosaurs of the Permian and the mammals of the ment that came from former ABT editor Jack Carter, and from

ORIGIN OF THE IDEA OF THE MAMMAL-LIKEREPTILE 29 the late Sam Gadd, who was particularly interested in this pro- particuliere. 44 vol., de l'ImprimerieRoyale, Paris. ject. Certainly my thanks go as well to the present staff of ABT COLBERT,E. E. 1969. Evolution of the vertebrates,2nd ed. John for a skillful and promptdisposition of the manuscript.All, how- Wiley & Sons, Inc., New York. ever, are absolved from responsibility for any residue of error, . 1972a. Lystrosaurus and Gondwanaland. In Dobzhansky and eccentricity of interpretation. This study was generously et al. eds., vol 6, p. 157-177 (see below). supportedby the Department of Natural Science, Loyola Univer- . 1972b. Antarctic fossils and the reconstruction of Gond- sity, Chicago. wanaland. Natural History 81(1):66. . 1973. Wandering lands and animals. E. P. Dutton & Co., New York. REFERENCES COPE, E. D. 1870. On the homologiesof some of the cranial bones ANON. 1968. Bain, Andrew Geddes. In Dictionary of South Af- of the Reptilia, and on the systematic arrangementof the class. rican biography,vol. 1. Proceedingsof the AmericanAssociation for the Advancementof AULIE, Richard P. 1972. The doctrine of special creation. Ameri- Science 19:194. can Biology Teacher34 (4): 191 and (5): 261. . 1878. The theromorphous Reptilia. American Naturalist BAIN, A. G. 1844. Letter to Sir Henry de la Beche, Foreign Sec- 12:829. retary to the London Geological Society, April 29th, 1844. In . 1884a The origin of the Mammalia. American Naturalist Lister 1949, p. 219-237 (see below). 18:1136. . 1856a [1845-56]. On the discovery of the fossil remains . 1884b. The relations between the theromorphous reptiles of bidental and other reptiles in South Africa. (Abridgmentof and the monotreme Mammalia. Proceedings of the American above letter, read Jan. 8, 1845). Transactionsof the Geological Association /br the Advancementof Science 33:471. . 1885. On the evolution of the Vertebrata, progressive

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Taylor, London. . 1887. On the skull and dentition of a Triassic Saurian . 1856a [1845-56]. Report on the reptilian fossils of South (Galesaurus planiceps, Ow.) Quarterly Journal of the Geological Africa. Transactions of the Geological Society of London (series Society of London 43:1. 2), vol. 7. Part I, Description of certain fossil crania, discovered OWEN, REV. R. 1894. The life of Richard Owen. 2 vol., D. Apple- by A. G. Bain, Esq., in sandstone rocks at the south-eastern ton & Co., New York. extremity of Africa, referable to different species of an extinct PARRINGTON, F. R. 1949. Remarks on a theory of the evolution genus of Reptilia (Dicynodon), and indicative of a new tribe or of the tetrapod middle ear. Journal of Laryngology and Otology sub-order of Sauria. (Read Jan. 8, 1845), p. 59. 63:580. . 1856b. Report . . ., Part II, Description of the skull of a . 1955. On the cranial anatomy of the gorgonopsids and large species of Dicynodon (D. tigriceps, Ow.), transmitted from the synapsid middle ear. Proceedings of the Zoological Society South Africa, by A. G. Bain, Esq. (Read May 16, 1865), p. 233. of London 125:1. . 1856c. Report . . ., Part III, On parts of the skeleton of the PEYER, B. 1968. Comparative odontology. Translated by Rainer trunk of the Dicynodon tigriceps. (Read June 13, 1855), p. 241. Zangerl. University of Chicago Press, Chicago. .___1858. President's address. Report of the British Association PRICE, D. J. 1962. The exponential curve of science. In The Soci- for the Advancement of Science, p. xlvix. John Murray, London. ology of Science, ed. by B. Barber and W. Hirsch. The Free Press .__ 1859. Palaeontology. Encyclopedia Britannica, 8th ed., of Glencoe, Macmillan Co., New York. vol. 17, p. 91. Little, Brown & Co., Boston. REED, C. A. 1960. Polyphyletic or monophyletic ancestry ofmain-

ORIGIN OF THE IDEA OF THE MAMMAL-LIKEREPTILE 31 mals, or: what is a class? Evolution 14(3):314. HONORARY MEMBERSHIP IN N.A.B.T. ROGERS,A. W. 1936. The pioneers in South African geology and FOWLER their work. Transactions of the Geological Society of South AWARDED H. SEYMOUR Africa 39 (Annexure):1. ROMER,A. S. 1966. Vertebratepaleontology, 3rd ed. University of Chicago Press, Chicago. H. Seymour Fowler was elected Honorary Member of 1968a. Osteology of the reptiles. University of Chicago the National Association of Biology Teachers at the 1974 Press, Chicago. annual meeting of the Board of Directors and was pre- 1968b. Notes and comments on vertebrate paleontology. sented this award at the NABT convention in New York. University of Chicago Press, Chicago. RUDWICK, M. J. S. 1972. The meaning of fossils. American H. Seymour ("Bus") Fowler was Elsevier, Inc., New York. born in Highland Park, Mich. He RUSSELL, E. S. 1916. Form and function: a contributionto the completed requirements for the B.S. history of animal morphology.John Murray & Sons, London. degree at Cornell University in SEELEY, H. G. 1889. Researches on the structure, organization, Ninth and classification of the fossil Reptilia (10 parts, 1888-96). 1941. After serving in the Part 6, On the anomodontReptilia and their allies, Philosoph- Infantry Division in French Mor- ical Transactionsof the Royal Societyof LondonB, 180:215. rocco, Algeria, Tunisia, Belgium,, . 1892. Researches . . ., Part 7, Further Observations on Sicily, France, and Germany, he Pareiasaurus, Philosophical Transactionsof the Royal Society and completed of London B, 183:311. returned to Cornell the requirement for a M.S. in 1946. 1894. Researches..., Part 9, Section 1, On the Therosucia, Downloaded from http://online.ucpress.edu/abt/article-pdf/37/1/21/32569/4445038.pdf by guest on 26 September 2021 and Section 2, The reputed mammals from the Karroo forma- After teaching high school chemistry tion of Cape Colony, Philosophical Transactions of the Royal for four years, Dr. Fowler again returned to Cornell and Society of London B, 185(2):987. was awarded his Ph.D. in 1951. . 1895a. Researches . . ., Part 9, Section 5, On the skeleton edu- in new Cynodontiafrom the Karroorocks, Philosophical Trans- Through the years Dr. Fowler has contributed to actions of the Royal Society of London B, 186(1):59. cation in a multitude of ways. As a charter member of the 1895b [1895-96]. Researches..., Part 10, On the complete National Association of Biology Teachers, Dr. Fowler has skeleton of the anomodont reptile (AristodesmusRutimeyeri, unselfishly served the NABT, whether working as Mid- Wiedersheim),from the Bunter sandstone of Reiken near Basel, west Membership Chairman (1954) or as a Regional giving new evidence of the relation of the Anomodontiato the Monotremata. Proceedings of the Royal Society of London Director(1971-74). He has held office in many educational 59:167. associations and is presently the editor of the Newsletter SIMPSON,G. G. 1959a. Anatomy and morphology:classification for the National Association for Research in Science and evolution in 1859 and 1959. Proceedings of the American Teaching. In international education Dr. Fowler has Philosophical Society 103:286. . 1959b. Mesozoic mammals and the polyphyletic origin of served as a Fulbright Lecturer in Science Education in the mammals. Evolution 13(3):405. Republic of Korea. There he received citations from the 1960. Diagnosis of the classes Reptilia and Mammalia. Korean government for his work in revising the high Evolution 14(3):388. school science curriculum. Probably Dr. Fowler's most 1961. Principles of animal taxonomy. Columbia University has been in preparing the revised Press, New York. monumental work . 1964. This view of life. Harbinger Book, Harcourt, Brace second edition, of E. L. Palmer's Fieldbook of Natural & World,Inc., New York. History, published by McGraw-Hill. SOLLAS,I. B. J., and W. J. SOLLAS.1914. A study of the skull of Presently, Dr. Fowler is Professor of Science Education a Dicynodon by serial sections. Philosophical Transactionsof at Penn State University. He continues, untiringly, to the Royal Society of London B, 204:201. in science educa- VAN VALEN, L. 1960. Therapsids as mammals. Evolution devote his time and energy to his work 14(3):304. tion, conservation, and a wide variety of organizations. WATSON, D. M. S. 1942. On Permian and Triassic Tetrapods. Possibly the best insight given of the man to whom we GeologicalMagazine 79:81. present this award was made in a letter of support of 1952. Robert Broom, 1866-1951. Obituary Notices of Fowler's nomination for Honorary Membership by Fellows of the Royal Society8(21):37. Dr. , and A. S. ROMER. 1956. A classification of therapsid Phillip R. Fordyce, Provost, Florida State University, reptiles. Bulletin of the Museum of Comparative Zoology when he wrote: 114(2):35. Perhaps nothing demonstrated Bus' professionalism WILBERFORCE,S. 1860. Darwin's Origin of Species. Quarterly more than a time many years ago when we were both a Review 108:225. candidate for the presidency of NABT, upon my election WOODWARD,H. B. 1908. The history of the GeologicalSociety I not have asked for a more loyal, helpful, and London. & could of Longmans, Green, Co., New York. considerate supporter than he. This behavior says much about the man and his professional quality....

The committee is pleased to have made this recom- mendation. Talent Loves Company GeorgeDawson, Chairman NABT Honorary Membership Committee The best things come, as a general rule, from talents that are members of a group;every man works best when he has companions working in the same line, and yielding she stimulus of suggestion, comparison,emulation. Henry James

32 THE AMERICAN BIOLOGY TEA-HER, JANUARY 1975