Newly recovered fossils confirm that Drepanosaurus, a prehistoric cross between a chameleon and an anteater, was a small reptile with a fearsome finger. The second digit of its forelimb sported a massive claw. (more…)
Understanding the planet’s history is crucial if we are to predict its future. While some records are preserved in ice cores or tree rings, other records of the climate’s ancient past are buried deep in the seafloor. (more…)
ANN ARBOR — Like salmon in reverse, long-snouted Bandringa sharks migrated downstream from freshwater swamps to a tropical coastline to spawn 310 million years ago, leaving behind fossil evidence of one of the earliest known shark nurseries.
That’s the surprising conclusion of University of Michigan paleontologist Lauren Sallan and a University of Chicago colleague, who reanalyzed all known specimens of Bandringa, a bottom-feeding predator that lived in an ancient river delta system that spanned what is today the Upper Midwest. (more…)
COLUMBUS, Ohio — Though scientists have long believed that complex organic molecules couldn’t survive fossilization, some 350-million-year-old remains of aquatic sea creatures uncovered in Ohio, Indiana, and Iowa have challenged that assumption.
The spindly animals with feathery arms—called crinoids, but better known today by the plant-like name “sea lily”—appear to have been buried alive in storms during the Carboniferous Period, when North America was covered with vast inland seas. Buried quickly and isolated from the water above by layers of fine-grained sediment, their porous skeletons gradually filled with minerals, but some of the pores containing organic molecules were sealed intact. (more…)
Patterns Also Shed Light on How Environmental Disturbances Affect Aquatic Organisms
The ability of deep-sea corals to harbor a broad array of marine life, including commercially important fish species, make these habitat-forming organisms of immediate interest to conservationists, managers, and scientists. Understanding and protecting corals requires knowledge of the historical processes that have shaped their biodiversity and biogeography.
While little is known about these processes, new research described in the journal Molecular Ecology helps elucidate the historical patterns of deep-sea coral migration and gene flow, coincident with oceanic circulation patterns and events. The investigators propose a scenario that could explain the observed evolutionary and present-day patterns in certain coral species. The findings can help scientists determine how climate change and other global processes have affected ocean habitats in the past and how they might do so in the future. (more…)
A fossil unearthed in Great Britain may end a long-running debate about the mollusks, one of life’s most diverse invertebrate groups: Which evolved first, shelled forms like clams and snails, or their shell-less, worm-like relatives?
The small new fossil, found in marine rocks along the English-Welsh border, provides the best fossil evidence yet that the simpler worm-like mollusks evolved from their more anatomically complex shelled brethren, rather than the other way around. (more…)
Trees Face Rising Drought Stress and Mortality as Climate Warms
LOS ALAMOS, N.M. — Combine the tree-ring growth record with historical information, climate records, and computer-model projections of future climate trends, and you get a grim picture for the future of trees in the southwestern United States. That’s the word from a team of scientists from Los Alamos National Laboratory, the U.S. Geological Survey, University of Arizona, and other partner organizations.
The research, published in Nature Climate Change this week, concluded that if the Southwest is warmer and drier in the near future, widespread tree mortality likely will cause substantial changes in forest and species distributions. (more…)
Another look at a nearly 80-year-old pottery collection at the Arizona State Museum is yielding new information about migrants who abandoned the Four Corners region.
Approximately eight centuries ago, people living along the Colorado Plateau in what is now the Four Corners area faced a crisis. Environmental changes that devastated their agricultural practices and likely aggravated social unrest forced significant numbers of these people to move away.
Many of them headed south into central and southern Arizona and western New Mexico, into lands already inhabited by well-established groups.
What is remarkable about this diaspora is that while there is no written record of what happened, much of what archaeologists know is told in the ceramic bowls, plates and figurines that were created and left behind when those civilizations later collapsed. (more…)
