Robert E. Sloan

Cretaceous Mammals from Montana

A series of Cretaceous mammal faunas, beginning with standard late Cretaceous faunas and continuing with three of Paleocene aspect, are summarized. Four families (Eucosmodontidae, Taeniolabididae, Leptictidae, Arctocyonidae) and one order (Condylarthra) of Tertiary mammals are extended into the Cretaceous. New genera Cimexomys, Stygimys, Procerberus, and Protungulatum are described, as is a small species of Catopsalis. The skeleton of a multituberculate is restored and multituberculate classification is revised.

Gradual Dinosaur Extinction and Simultaneous Ungulate Radiation in the Hell Creek Formation

Dinosaur extinction in Montana, Alberta, and Wyoming was a gradual process that began 7 million years before the end of the Cretaceous and accelerated rapidly in the final 0.3 million years of the Cretaceous, during the interval of apparent competition from rapidly evolving immigrating ungulates. This interval involves rapid reduction in both diversity and population density of dinosaurs. The last dinosaurs known are from a channel that contains teeth of Mantuan mammals, seven species of dinosaurs, and Paleocene pollen. The top of this channel is 1.3 meters above the likely position of the iridium anomaly, the Cretaceous/Tertiary boundary.

The Earliest Primates

The known range of the Primates is extended down from the middle Paleocene to the early Paleocene and late Cretaceous by a new genus and two new species from Montana, Purgatorius unio and P. ceratops. These species approach condylarths and leptictid and erinaceoid insectivores in structure. Purgatorius is referred to a new subfamily, Purgatoriinae, of the Paromomyidae, but is probably not the stem primate. The fauna of Purgatory Hill indicates a late early Paleocene age.

Comparative biochemical studies of milks— II. Dialyzable carbohydrates☆

Abstract 1. 1. Dialyzable non-ionized milk sugars from forty-nine placental and three marsupial species have been investigated chromatographically. Conspicuous taxonomic differences in proportions of sugars occur. 2. 2. The most characteristic placental sugar with some exceptions in lactose followed in amount by a component that appears to be a trisaccharide and in turn by glucose, galactose and various oligosaccharides. 3. 3. In the marsupial milks, lactose, although present, is not the predominant milk sugar. Free glucose, galactose and oligosaccharides are present in the milk of each marsupial species. With one minor exception, the oligosaccharides of the marsupial milks yielded both glucose and galactose on hydrolysis. None of them appeared to be pentoses or yielded fucose or pentoses upon hydrolysis. 4. 4. The marsupial milks were tested for bifidus activity using Lactobacillus bifidus var. pennsylvanicus and found active. Some 40–70 per cent of the bifidus activitiy occurred in small molecular weight (i.e. dialyzable) milk constituents. Bifidus activity decreased markedly with the stage of lactation.

Comparative biochemical studies of milks. I. Electrophoretic analysis of milk proteins.

Abstract 1. 1. Paper electrophoretic patterns of caseins and whey proteins from milks of forty species of mammals representing eight orders are presented. Each species has a distinct pattern and related species have similar patterns. 2. 2. Three types of casein patterns were found. The most primitive has a single fast-moving component which is strongly adsorbed by paper. The second type has a prominent slow-moving component and a faster component which is adsorbed. The third type has two sharply differentiated components. 3. 3. In eight species in which whey and blood serum were compared the whey contained components with the mobility of blood serum albumin and gamma globulins. 4. 4. Milks from the primitive orders contained fewer unique whey protein components than milks of more advanced orders. 5. 5. An electrophoretic component tentatively identified as lysozyme appears in whey protein patterns of certain carnivores and perissodactyls.

Prism Size in Tooth Enamel of Some Late Cretaceous Mammals and Its Value in Multituberculate Taxonomy

Teeth from specified members of the two suborders of Late Cretaceous Multituberculata and two Late Cretaceous therians were studied. The enamel was prismatic on all teeth. In the therian representatives and the representatives of the suborder Ptilodontoidea of the Multituberculata, the prism diameters and densities per unit area were similar to those of recent mammals. In the representatives of the suborder Taeniolabidoidea the prisms were very large and their density per unit area was 5 to 8 times lower than in recent mammals. It is suggested that gigantoprismatic enamel is a characteristic of Taeniolabidoidea and could be used as a taxonomic criterion in multituberculate systematics.

Comparative biochemical studies of milks—III. Immunoelectrophoretic comparisons of milk proteins of the artiodactyla

1. 1. Milk proteins from nineteen species of artiodactyls and from five other species have been examined immunoelectrophoretically versus rabbit antisera for milk proteins from Bos taurus. 2. 2. Milks of ruminants gave positive reactions to anti-cow β-lactoglobulin and anti-cow α-lactalbumin sera. Milks from non-ruminant artiodactyls and from perissodactyls, rodents, lagomorphs and primates did not react with these antisera. 3. 3. Milk proteins from both ruminant and non-ruminant species reacted with anti-cow serum albumin and anti-cow casein sera.