Castoroides

Abstract: A variety of estimators have been used by paleontologists for reconstructing body mass of fossil mammals. For rodents, the most commonly used proxy is m1 area, although that value is known to overestimate masses in muroid rodents and is generally problematic in rodent taxa in which the m1 is either enlarged (as in muroids) or reduced (as in extinct mylagaulids). This paper explores the potential utility of 2 alternative proxies, toothrow length and toothrow area; these measures are shown here to be very tightly correlated with body mass among rodents. Regression within certain clades of the Rodentia provides an even tighter fit. Applying these proxy measures to several fossil rodents provides an estimate of their masses. Comparison to published body masses of extinct rodents estimated from postcrania reveals that body masses for Castoroides and Palaeocastor estimated from femur length are consistent with those from dental proxies but that toothrow-based estimates for Phoberomys, the largest known...

Abstract: Estimating body size of extinct mammals presents problems when size can be estimated only by extrapolation. I examined the influence of phylogenetic, biomechanical, and statistical assumptions on body size estimates for 2 species of fossil castorids, the Pleistocene ‘‘giant’’ beaver Castoroides and the fossorial Miocene beaver Palaeocastor. Prior descriptions of Castoroides as ‘‘black-bear sized’’ were greatly exaggerated; new analyses estimated body masses at 60‐100 kg. Estimates for Palaeocastor were similar to previously published estimates (0.8‐1.2 kg). Biologically realistic size estimates were based on femur length and on interspecific data covering a wide range of body mass; skull length measurements or extrapolations from an ontogenetic single-species data set resulted in excessively large body mass estimates. Body mass must be estimated with due attention to the choice of both morphological trait and reference taxa.

Abstract: Vertebrate fossils have been collected for hundreds of years and are stored in museum collections around the world. These remains provide a readily available resource to search for preserved proteins; however, the vast majority of palaeoproteomic studies have focused on relatively recently collected bones with a well-known handling history. Here, we characterize proteins from the nasal turbinates of the first Castoroides ohioensis skull ever discovered. Collected in 1845, this is the oldest museum-curated specimen characterized using palaeoproteomic tools. Our mass spectrometry analysis detected many collagen I peptides, a peptide from haemoglobin beta, and in vivo and diagenetic post-translational modifications. Additionally, the identified collagen I sequences provide enough resolution to place C. ohioensis within Rodentia. This study illustrates the utility of archived museum specimens for both the recovery of preserved proteins and phylogenetic analyses.

Abstract: Vertebrate fossils and faunas that are reasonably inferred to be of last (Sangamonian) interglacial age are considered in geographic order from east to west to north in Canada. Data on localities, vertebrate taxa, stratigraphy, geochronology, paleoenvironment and paleoclimate are considered. Information on key faunas from Toronto, Fort Qu'Appelle, Saskatoon. Medicine Hat and Old Crow River is supplemented by data on smaller faunas and, in some cases, individual specimens. New data are included for several localities. Fishes, such as whitefish (Coregonus sp.) and pike (Esox sp.). had broad distributions from eastern to northwestern Canada. Except for a turtle (Emydoidea blandingi) from lnnerkip, Ontario, amphibians and reptiles have not yet been reported from Canada during the Sangamon Interglaciation. Several species of grouse-like birds (Tetraonidae) are known from western Canada. Among the mammals. American mastodons (Mammut americanum), mammoths (Mammuthus sp.), beavers (Castor canadensis), giant beavers (Castoroides ohioensis), muskrats (Ondatra zibethicus), voles (Microtus sp.). white-tailed deer (Odocoileus virginianus), stag moose (Cervalces sp.), bison [perhaps mainly giant bison (Bison latifrons)\ and muskoxen (Ovibovini) were evidently most widespread during the last interglacial interval. The western plains had a characteristic large mammal fauna that included Columbian mammoths (Mammuthus columbi), Scott's horses (Equus scotti), small horses (Equus conversidens), western camels (Camelops hesternus). pronghorns (Antilocapridae), giant bison (Bison latifrons) and helmeted muskoxen (Sy m bos cavifrons).