How do small birds evolve in response to climate change? Data from the long-term record at La Brea tar pits.

Biology textbooks describe the small changes in the beaks of the Galápagos finches as exemplars of how birds evolve in response to environmental changes. However, recent studies of the abundant fossil birds at Rancho La Brea find no evidence of evolutionary responses to the dramatic climate changes of the glacial-interglacial cycle over the past 35 000 years: none of the large birds exhibit any change in body size or limb proportions, even during the last glacial maximum approximately 18 000-20 000 years ago, when the southern California chaparral was replaced by snowy coniferous forests. However, these are all large birds with large ranges and broad habitat preferences, capable of living in many different environments.

Did saber-tooth kittens grow up musclebound? A study of postnatal limb bone allometry in felids from the Pleistocene of Rancho La Brea.

Previous studies have demonstrated that the Pleistocene saber-toothed cat Smilodon fatalis had many forelimb adaptations for increased strength, presumably to grapple with and subdue prey. The Rancho La Brea tar pits yield large samples of juvenile limb bones forming a growth series that allow us to examine how Smilodon kittens grew up. Almost all available juvenile limb bones were measured, and reduced major axis fits were calculated to determine the allometric growth trends.

Species longevity in North American fossil mammals.

Species longevity in the fossil record is related to many paleoecological variables and is important to macroevolutionary studies, yet there are very few reliable data on average species durations in Cenozoic fossil mammals. Many of the online databases (such as the Paleobiology Database) use only genera of North American Cenozoic mammals and there are severe problems because key groups (e.g.