In Pursuit of Early Mammals

6. Haramiyidans and Probable Related Forms

99 6 6.1. A Comparison of the left upper (A1 –D1 ) and right lower (A2 –D2 ) molariforms of Thomasia, Haramiyavia, Theroteinus, and Eleutherodon in occlusal views, illustrating cusp homologies postulated by Butler (2000). Numbering of cusps according to method introduced by Hahn and Hahn (1999). Labial is to the right and mesial above. On upper molariforms the cusps are numbered from distal to mesial and in lowers from mesial to distal, in accordance with their postulated homologies with Haramiyavia. On upper molariforms of Eleutherodon, the cusps BB and Bx are enlarged mesial cusps of the lingual (BB) and middle (B) rows, and A indicates the A (most mesial) row. Not to scale. Modified from Butler (2000). Haramiyidans and Probable Related Forms As early as 1847 Pleininger erected the genus Microlestes with a single species, M. antiquus, based on a minute, double-rooted tooth boasting two rows of cusps. It derived from the Upper Triassic beds (Norian-Rhaetian boundary) of Dagerlof, Württemberg, Germany. The name Microlestes was already occupied, as were other names subsequently erected to replace it, and it was later assigned to Thomasia Poche, 1908. Teeth of this type are common in the Late Triassic–Early Jurassic of Europe, and they resemble those of multituberculates in having numerous low cusps, arranged in rows. They differ from those of multituberculates in having cusps of various heights. The teeth referred to as Thomasia are relatively narrow. In addition to Thomasia, broader teeth assigned to the genus Haramiya also occur in the same sediments. Simpson (1947) placed both Thomasia (figure 6.1) and Haramiya in the family Haramiyidae. Hahn (1973) erected a separate suborder for the Haramiyidae, a Haramiyoidea, placed within the Multituberculata, and later (in Hahn et al. 1989) raised it to ordinal rank as Haramiyida. Heinrich (1999, 2001) described the genus Staffia based on isolated teeth from the Upper Jurassic (Kimmeridgian) Tendaguru beds of Tanzania (see figure 6.2C). The teeth of Staffia were obtained from the matrix, housed in the Natural History Museum in Berlin, collected by the German Tendaguru Expedition before the First World War, when Tanzania was a German colony (see Maier 2003). Kielan-Jaworowska et al. (2004) assigned Staffia to the Haramiyidae. Studies on Mesozoic mammals in France are associated with the name of Denise Sigogneau-Russell (figure 6.2E). Denise defended her Ph.D. thesis in 1969, a part of which was devoted to the gorgonopsians (therapsid reptiles) of South Africa, where she spent two years. In 1976, when a Belgian amateur brought her a mammal tooth from a quarry in eastern France, she changed the direction of her studies and began to search for Mesozoic mammals. She sought them with great initiative in France, Portugal, Madagascar, and, finally, in Morocco. In 1991 she published a book on Mesozoic mammals (Sigogneau-Russell 1991). The beginning of her work on Mesozoic mammals was at the locality Saint-Nicolas-de-Port in Lorraine (in northeastern France). In 1983 she published the first review (Sigogneau-Russell 1983a) of the fauna occurring there (whose remains were obtained by using the screen-washing technique). Subsequently she published a meticulous monograph In Pursuit of Early Mammals 100 describing about 200 isolated teeth that she obtained from the deltaic sediments of Rhaetic (Late Triassic) age from the same locality (Sigogneau -Russell 1989). She recognized among the investigated teeth three types of upper incisors and one type of lower, as well as upper and lower premolars and molars of haramiyids. Research on these faunas included rewarding collaboration with Gerhard and Renate Hahn. Currently, Sigogneau-Russell studies the British Mesozoic faunas with Percy M. Butler (figure 6.2F). Owing to her scholarship and diligence, she has contributed enormously to the knowledge of early mammal evolution. Farish A. Jenkins Jr. was born in New York and was the first scientist to employ cineradiography to study animal locomotion (figure 6.2D). Jenkins started university studies at Princeton, from which he graduated in 1961, and received his Ph.D. from Yale in 1968. In 1974 he was appointed professor of biology in the Department of Organismic and Evolutionary Biology at Harvard. In 1989 he was awarded the title of Alexander Agassiz Professor of Zoology. Jenkins published over 100 original papers, some of which are comprehensive monographs. He has been working on different groups of vertebrates, both fossil and extant, and most of his papers are innovative. He is also an active field researcher, mostly in Mesozoic deposits. He has described numerous Mesozoic mammals. Especially interesting...