COLLEGE PARK, Md. – By reptile standards, alligators are positively chatty. They are the most vocal of the non-avian reptiles and are known to be able to pinpoint the source of sounds with accuracy. But it wasn’t clear exactly how they did it because they lack external auditory structures.
In a new study, an international team of biologists shows that the alligator’s ear is strongly directional because of large, air-filled channels connecting the two middle ears. This configuration is similar in birds, which have an interaural canal that increases directionality. (more…)
Air flows mostly in a one-way loop through the lungs of monitor lizards – a breathing method shared by birds, alligators and presumably dinosaurs, according to a new University of Utah study.
The findings – published online Wednesday, Dec. 11 in the journal Nature – raise the possibility this breathing pattern originated 270 million years ago, about 20 million years earlier than previously believed and 100 million years before the first birds. Why remains a mystery. (more…)
COLUMBIA, Mo. — Crocodilians have nerves on their faces that are so sensitive, they can detect a change in a pond when a single drop hits the water surface several feet away. Alligators and crocodiles use these “invisible whiskers” to detect prey when hunting. Now, a new study from the University of Missouri has measured the nerves responsible for this function, which will help biologists understand how today’s animals, as well as dinosaurs and crocodiles that lived millions of years ago, interact with the environment around them. (more…)
Answer may be ‘adaptive zones’ that limit species number, life scientists report
There are more than 400,000 species of beetles and only two species of the tuatara, a reptile cousin of snakes and lizards that lives in New Zealand. Crocodiles and alligators, while nearly 250 million years old, have diversified into only 23 species. Why evolution has produced “winners” — including mammals and many species of birds and fish — and “losers” is a major question in evolutionary biology.
Scientists have often posited that because some animal and plant lineages are much older than others, they have had more time to produce new species (the dearth of crocodiles notwithstanding). This idea — that time is an important predictor of species number — underlies many theoretical models used by biologists. However, it fails to explain species numbers across all multi-cellular life on the planet, a team of life scientists reports Aug. 28 in the online journal PLoS Biology, a publication of the Public Library of Science. (more…)
UD’s Schmidt studies genome of crocodile family in evolution research
University of Delaware scientist Carl Schmidt is working to identify genes in crocodiles, alligators and gharials as he searches for links between the creatures that could give clues as to how they evolved over the years in relation to one another.
Schmidt’s effort is part of a National Science Foundation-funded project being conducted by a team of researchers assembled by David Ray, an evolutionary biologist at Mississippi State University. (more…)
HOMESTEAD, Fla. — Precipitous declines in formerly common mammals in Everglades National Park have been linked to the presence of invasive Burmese pythons, according to a study published on Jan. 30, 2012, in the Proceedings of the National Academy of Sciences.
The study, the first to document the ecological impacts of this invasive species, strongly supports that animal communities in this 1.5-million-acre park have been markedly altered by the introduction of pythons within 11 years of their establishment as an invasive species. Mid-sized mammals are the most dramatically affected. (more…)
*Some Dinosaurs Were as Warm as Most Modern Mammals*
PASADENA, Calif.—Were dinosaurs slow and lumbering, or quick and agile? It depends largely on whether they were cold or warm blooded. When dinosaurs were first discovered in the mid-19th century, paleontologists thought the y were plodding beasts that had to rely on their environments to keep warm, like modern-day reptiles. But research during the last few decades suggests that they were faster creatures, nimble like the velociraptors or T. rex depicted in the movie Jurassic Park, requiring warmer, regulated body temperatures like in mammals.
Now, a team of researchers led by the California Institute of Technology (Caltech) has developed a new approach to take body temperatures of dinosaurs for the first time, providing new insights into whether dinosaurs were cold or warm blooded. By analyzing isotopic concentrations in teeth of sauropods, the long-tailed, long-necked dinosaurs that were the biggest land animals to have ever lived—think Apatosaurus (also known as Brontosaurus)—the team found that the dinosaurs were about as warm as most modern mammals. (more…)
SANTA FE, N.M.— Garbage mounds left by prehistoric humans might have driven the formation of many of the Florida Everglades’ tree islands, distinctive havens of exceptional ecological richness in the sprawling marsh that are today threatened by human development.
Tree islands are patches of relatively high and dry ground that dot the marshes of the Everglades. Typically a meter (3.3 feet) or so high, many of them are elevated enough to allow trees to grow. They provide a nesting site for alligators and a refuge for birds, panthers, and other wildlife. (more…)
