Publications by authors named "Jim I Mead"
Article Synopsis
- Living sloths are part of two separate lineages that evolved from land-dwelling ancestors into tree-dwelling animals, with six species remaining today after the extinction of larger relatives at the end of the Quaternary period.
- Researchers used ancient DNA to sequence the mitogenomes of 10 extinct sloth species, revealing eight distinct lineages that differ significantly from previous morphological classifications.
- The findings show that Caribbean sloths have distinct evolutionary roots and that living three-fingered sloths share a closer relation to extinct ground sloths than previously thought, offering new insights into sloth evolution and biogeography.
The relationship between body size and temperature of mammals is poorly resolved, especially for large keystone species such as bison (). are well represented in the fossil record across North America, which provides an opportunity to relate body size to climate within a species. We measured the length of a leg bone (calcaneal tuber, DstL) in 849 specimens from 60 localities that were dated by stratigraphy and C decay.
View Article and Find Full Text PDFWe report 95 vertebrate taxa (13 fishes, 11 reptiles, 63 birds, 8 mammals) from late Pleistocene bone deposits in Sawmill Sink, Abaco, The Bahamas. The >5,000 fossils were recovered by scuba divers on ledges at depths of 27-35 m below sea level. Of the 95 species, 39 (41%) no longer occur on Abaco (4 reptiles, 31 birds, 4 mammals).
View Article and Find Full Text PDFBighorn sheep (Ovis canadensis) were not known to live on Tiburón Island, the largest island in the Gulf of California and Mexico, prior to the surprisingly successful introduction of 20 individuals as a conservation measure in 1975. Today, a stable island population of ∼500 sheep supports limited big game hunting and restocking of depleted areas on the Mexican mainland. We discovered fossil dung morphologically similar to that of bighorn sheep in a dung mat deposit from Mojet Cave, in the mountains of Tiburón Island.
View Article and Find Full Text PDFThe emergence of new technologies and improved computing power helped to introduce a renewed vitality in morphological research in recent decades. This is especially apparent in the new advances made in understanding the evolutionary morphology of the skeletal system in extinct and extant squamate reptiles. The new data generated as a result of the recent increase in attention are relevant not only for systematic analyses but also are valuable in their own right for contributing to holistic perspectives on organismal evolution, mosaic evolution in the rates of change in different anatomical systems, and broader patterns of macroevolution.
View Article and Find Full Text PDFArticle Synopsis
- Scientists discovered a lot of old animal fossils in Porcupine Cave, Colorado, which help us understand how animals reacted to climate changes long ago.
- They found 127 different animal species from the mid-Pleistocene period, including 30 that were seen for the first time.
- The research showed that smaller animals were more affected by warming climates, but the overall balance of animal communities stayed stable for a really long time, even before humans came along.