Only one site in Africa, Tendaguru, in eastern Tanzania (figure 2.6) has thus far yielded Late Jurassic mammals. Tendaguru was worked for its dinosaurs, most notably by a German team between 1909 and 1913, and yielded Brachiosaurus and Barosaurus (both also found in the Morrison Formation of the western United States), among others. In addition to individual skeletal elements, the expedition brought back rock matrix containing dinosaur bones—a fortunate circumstance as the rock proved to contain fossils of mammals and other small vertebrates in addition to the specimens then considered of primary interest. The Tendaguru beds include three units that have yielded dinosaurs, the lower, middle, and upper saurian beds (Janensch, 1914), which are considered to represent brackish to limnic deposits and to be Kimmeridgian to Tithonian, Late Jurassic (Russell et al., 1980; Heinrich, 1998). A review of the geology and paleontology of Tendaguru is given by Heinrich et al. (2001).

The first mammal to be reported from Tendaguru is Brancatherulum tendagurense, from the upper saurian bed (Heinrich, 1998), described by Dietrich (1927) and later discussed by Simpson (1928e) and Heinrich (1991). Brancatherulum has been referred to the "eupantotherian" family Peramuridae (see discussion by Kraus, 1979), which are thought to be close relatives of northern tribosphenic mammals (chapter 10). Given that the only known specimen is an edentulous dentary, the affinities of Bran-catherulum are uncertain.

Additional mammals from Tendaguru have recently been described by Heinrich (1998), based on specimens from the middle saurian bed. Tendagurodon janenschi, known from a lower molariform tooth, is a "triconodont" tentatively considered here as a member of "Amphilesti-dae" (chapter 7). Tendagurutherium dietrichi is represented by the posterior part of a dentary with most of the last tooth intact; it is tentatively referred to the Peramuri-dae (see Heinrich, 1998), which are otherwise known from the Early Cretaceous of Africa and Britain, the Middle Jurassic of Britain, and the Late Jurassic of Portugal. Staffia aenigmatica is known by three teeth—a lower premolar, a lower molar, and an upper molar (Heinrich, 2001). This taxon is significant in that it is referred to the Haramiyi-dae (see chapter 8), which are otherwise known only from the Late Triassic-Early Jurassic of northern landmasses (Heinrich, 1999). Presence of this group in the Jurassic of Africa provides another possible source for enigmatic possibly allotherian groups of the southern continents, such as gondwanatherians.

0 0

Post a comment