A new specimen-dependent method of estimating felid body mass

Background. The estimation of body mass of long extinct species of the family Felidae has been a focus of paleontology. However, most utilized methods impose expected proportions on the fossil specimens being estimated, resulting in a high chance of underestimation or overestimation. This study proposes a new method of estimating felid body mass by accounting for osteological proportionality differences between the extinct taxa being estimated and the living species being used as comparisons. Method. Using a manipulation of the cube law, 36 equations were formulated that estimate body mass based on certain humeral and femoral dimensions. The formulated equations were used to examine whether the mass of living comparison species, namely the tiger (Panthera tigris), the lion (Panthera leo), and the jaguar (Panthera onca), depends equally on a select set of long bone dimensions. The body mass of five extinct felids, namely Panthera atrox, Panthera spelaea, Panthera tigris soloensis, Smilodon populator, and Smilodon fatalis, was also estimated. Results. Living comparisons species were found to somewhat incorrectly estimate other living comparison species. All five extinct taxa were found to weigh well over 300 kg, with the largest of the species weighing nearly 500 kg. Discussion. The inability of one living comparison species to predict the mass of another with strong accuracy suggests that bone dimensions do not solely influence body mass. Discrepancies between the masses of Smilodon populator and Smilodon fatalis were likely the product of the difference in available niches in late Pleistocene North and South America. The masses of Panthera spelaea and Panthera atrox indicate a discrepancy in sociality between the two closely related species. Lastly, the extreme body mass of Panthera tigris soloensis points to great plasticity within the tiger lineage in terms of size, indicating that such variations among tiger populations may not warrant subspeciation.

A new specimen-dependent method of estimating felid body mass

Background. The estimation of body mass of long extinct species of the family Felidae has been a focus of paleontology. However, most utilized methods impose expected proportions on the fossil specimens being estimated, resulting in a high chance of underestimation or overestimation. This study proposes a new method of estimating felid body mass by accounting for osteological proportionality differences between the extinct taxa being estimated and the living species being used as comparisons. Method. Using a manipulation of the cube law, 36 equations were formulated that estimate body mass based on certain humeral and femoral dimensions. The formulated equations were used to examine whether the mass of living comparison species, namely the tiger (Panthera tigris), the lion (Panthera leo), and the jaguar (Panthera onca), depends equally on a select set of long bone dimensions. The body mass of five extinct felids, namely Panthera atrox, Panthera spelaea, Panthera tigris soloensis, Smilodon populator, and Smilodon fatalis, was also estimated. Results. Living comparisons species were found to somewhat incorrectly estimate other living comparison species. All five extinct taxa were found to weigh well over 300 kg, with the largest of the species weighing nearly 500 kg. Discussion. The inability of one living comparison species to predict the mass of another with strong accuracy suggests that bone dimensions do not solely influence body mass. Discrepancies between the masses of Smilodon populator and Smilodon fatalis were likely the product of the difference in available niches in late Pleistocene North and South America. The masses of Panthera spelaea and Panthera atrox indicate a discrepancy in sociality between the two closely related species. Lastly, the extreme body mass of Panthera tigris soloensis points to great plasticity within the tiger lineage in terms of size, indicating that such variations among tiger populations may not warrant subspeciation.

A new specimen-dependent method of estimating felid body mass

Background. The estimation of body mass of long extinct species of the family Felidae has been a focus of paleontology. However, most utilized methods impose expected proportions on the fossil specimens being estimated, resulting in a high chance of underestimation or overestimation. This study proposes a new method of estimating felid body mass by accounting for osteological proportionality differences between the extinct taxa being estimated and the living species being used as comparisons. Method. Using a manipulation of the cube law, 36 equations were formulated that estimate body mass based on certain humeral and femoral dimensions. The formulated equations were used to examine whether the mass of living comparison species, namely the tiger (Panthera tigris), the lion (Panthera leo), and the jaguar (Panthera onca), depends equally on a select set of long bone dimensions. The body mass of five extinct felids, namely Panthera atrox, Panthera spelaea, Panthera tigris soloensis, Smilodon populator, and Smilodon fatalis, was also estimated. Results. Living comparisons species were found to somewhat incorrectly estimate other living comparison species. All five extinct taxa were found to weigh well over 300 kg, with the largest of the species weighing nearly 500 kg. Discussion. The inability of one living comparison species to predict the mass of another with strong accuracy suggests that bone dimensions do not solely influence body mass. Discrepancies between the masses of Smilodon populator and Smilodon fatalis were likely the product of the difference in available niches in late Pleistocene North and South America. The masses of Panthera spelaea and Panthera atrox indicate a discrepancy in sociality between the two closely related species. Lastly, the extreme body mass of Panthera tigris soloensis points to great plasticity within the tiger lineage in terms of size, indicating that such variations among tiger populations may not warrant subspeciation.

First occurrence of <i>Panthera atrox</i> (Felidae, Pantherinae) in the Mexican state of Hidalgo and a review of the record of felids from the Pleistocene of Mexico

Panthera atrox was a common large-sized cat in North America during the late Pleistocene. An isolated lower canine and a fifth metacarpal bone referable to this species were recovered from fluvial Quaternary deposits that outcrop in southeastern Hidalgo, central Mexico. Associated fossil material belonging to Bison indicates a Rancholabrean North American Land Mammal Age; the age assignment is corroborated by the presence of P. atrox. A comparative study with selected specimens of Panthera and Smilodon indicates that the Hidalgoan sample shares the following diagnostic features with P. atrox: a large, robust, and non-strongly curved lower canine; a large and relatively slender fifth metacarpal with a well-developed projection on the palmar side at the proximal end, narrow articulating surface for the unciform; a narrow notch on the articulating surface for the fourth metacarpal; and a diaphysis that at the middle is oval in cross section. The record supplements the evidence of P. atrox in central Mexico and represents the first reported occurrence of this cat species in the state of Hidalgo. By the same token, the known geographic distribution of P. atrox in the Mexican territory suggests that it was relatively common in temperate areas of central Mexico between 19 and 24° N at an altitudinal range from 1500 to 2250 m a.s.l. The large size (mean body mass of 300 kg) and hypercarnivorous adaptations of the American lion suggest it was the top predator of the mammalian community recorded at southeastern Hidalgo, displacing other members of the carnivore guild at the mesopredator level, such as the dire wolf (Canis dirus ), which has been also reported in the area. The high diversity of large herbivores recorded at southeastern Hidalgo, which in turn could represent potential prey of P. atrox, suggests that some areas that now are part of central Mexico were suitable hunting sites for this large-sized cat. A review of the Pleistocene record of Felidae from Mexico revealed that it encompasses 87.5 and 73.3 % of generic and specific diversity known for North America, respectively, including seven genera (Felis, Miracinonyx, Panthera, Puma, Lynx, Leopardus, and Smilodon) and 11 species (Felis rexroadensis, Miracinonyx inexpectatus, Panthera atrox, Panthera onca, Puma concolor, Puma yagouaroundi, Lynx rufus, Leopardus pardalis, Leopardus wiedii, Smilodon fatalis, and Smilodon gracilis). The majority of these taxa have been reported from numerous late Pleistocene localities; in particular, Panthera atrox was relatively common and widely distributed across the Mexican territory.

Endocranial Morphology of the Extinct North American Lion (Panthera atrox)

The extinct North American lion (Panthera atrox) is one of the largest felids (Mammalia, Carnivora) to have ever lived, and it is known from a plethora of incredibly well-preserved remains. Despite this abundance of material, there has been little research into its endocranial anatomy. CT scans of a skull of P. atrox from the Pleistocene La Brea Tar pits were used to generate the first virtual endocranium for this species and to elucidate previously unknown details of its brain size and gross structure, cranial nerves, and inner-ear morphology. Results show that its gross brain anatomy is broadly similar to that of other pantherines, although P. atrox displays less cephalic flexure than either extant lions or tigers, instead showing a brain shape that is reminiscent of earlier felids. Despite this unusual reduction in flexure, the estimated absolute brain size for this specimen is one of the largest reported for any felid, living or extinct. Its encephalization quotient (brain size as a fraction of the expected brain mass for a given body mass) is also larger than that of extant lions but similar to that of the other pantherines. The advent of CT scans has allowed nondestructive sampling of anatomy that cannot otherwise be studied in these extinct lions, leading to a more accurate reconstruction of endocranial morphology and its evolution.

Cougars’ key to survival through the Late Pleistocene extinction: insights from dental microwear texture analysis

Cougars ( Puma concolor ) are one of only two large cats in North America to have survived the Late Pleistocene extinction (LPE), yet the specific key(s) to their relative success remains unknown. Here, we compare the dental microwear textures of Pleistocene cougars with sympatric felids from the La Brea Tar Pits in southern California that went extinct at the LPE ( Panthera atrox and Smilodon fatalis ), to clarify potential dietary factors that led to the cougar's persistence through the LPE. We further assess whether the physical properties of food consumed have changed over time when compared with modern cougars in southern California. Using dental microwear texture analysis (DMTA), which quantifies surface features in three dimensions, we find that modern and Pleistocene cougars are not significantly different from modern African lions in any DMTA attributes, suggesting moderate durophagy (i.e. bone processing). Pleistocene cougars from La Brea have significantly greater complexity and textural fill volume than Panthera atrox (inferred to have primarily consumed flesh from fresh kills) and significantly greater variance in complexity values than S. fatalis . Ultimately, these results suggest that cougars already used or adopted a more generalized dietary strategy during the Pleistocene that may have been key to their subsequent success.

Imperial Mammoth and Mexican Half-Ass from near Bindloss, Alberta

Mammals recovered from gravels lying about 100 ft (30 m) above the level of the Red Deer River on Highway 41, halfway between Bindloss and Empress, now comprise Mammuthus imperator and Equus (Asinus) conversidens in addition to the lion-like cat (Panthera atrox) previously recorded from the site. A post-Wisconsin age of greater than 8000 years B.P. is suggested for the deposit.