Joyce W.G.,University of Tubingen |
Parham J.F.,California State University, Fullerton |
Lyson T.R.,Yale Peabody Museum of Natural History |
Lyson T.R.,Smithsonian Institution |
And 4 more authors.
Journal of Paleontology | Year: 2013
Turtles have served as a model system for molecular divergence dating studies using fossil calibrations. However, because some parts of the fossil record of turtles are very well known, divergence age estimates from molecular phylogenies often do not differ greatly from those observed directly from the fossil record alone. Also, the phylogenetic position and age of turtle fossil calibrations used in previous studies have not been adequately justified. We provide the first explicitly justified minimum and soft maximum age constraints on 22 clades of turtles following best practice protocols. Using these data we undertook a Bayesian relaxed molecular clock analysis establishing a timescale for the evolution of crown Testudines that we exploit in attempting to address evolutionary questions that cannot be resolved with fossils alone. Some of these questions, such as whether the turtle crown originated in the Triassic or Jurassic, cannot be resolved by our analysis. However, our results generate novel age-of-origination estimates for clades within crown Testudines. Finally, we compare our fossil calibrations and posterior age estimates to those from other studies, revealing substantial differences in results and interpretation.Copyright © 2013, The Paleontological Society. Source
Brazaitis P.,Yale Peabody Museum of Natural History |
Watanabe M.E.,Naugatuck Valley Community College
Historical Biology | Year: 2011
Modern crocodilians and birds are the only living representatives of the Archosauria, a group that also includes non-avian dinosaurs and pterosaurs. Modern crocodilians originated during the early Cretaceous period and dispersed globally. Examples of physiological similarities between living crocodilians and birds include similar amino acids in b-keratins among crocodiles, turtles and birds; oviduct homologies between crocodilians and birds; similar forelimb structures in crocodiles and other archosaurs and similarities in gene expression in limb development in alligators and chickens. While individual crocodilian species have adapted their behaviours to meet specific strategies for survival in specific habitats, core reproductive behaviours are universal among modern crocodilians and transcend speciation, morphology and geographic distribution. Hard-wired core behaviours include social signals that incorporate chemosensory, auditory and mechanoreception modalities; construction of a temperature-stabilising nest chamber to incubate eggs; and parental care of their young. Parental care may reflect a primitive character for archosaurs, including dinosaurs. Crocodilians use integumentary sense organs (ISOs) during courtship and in parental care, and similar structures may have had similar functions in dinosaurs. The presence of numerous foramina (possible ISOs) in the skulls of saurischians, along with the findings of fossilised nests with adults, may indicate similar complex behaviours, including parental care, in dinosaurs. © 2011 Taylor & Francis. Source
Ague J.J.,Yale University |
Nicolescu S.,Yale Peabody Museum of Natural History
Nature Geoscience | Year: 2014
The balance between the subduction of carbonate mineral-bearing rocks into Earth's mantle and the return of CO2 to the atmosphere by volcanic and metamorphic degassing is critical to the carbon cycle. Carbon is thought to be released from subducted rocks mostly by simple devolatilization reactions. However, these reactions will also retain large amounts of carbon within the subducting slab and have difficulty in accounting for the mass of CO2 emitted from volcanic arcs. Carbon release may therefore occur via fluid-induced dissolution of calcium carbonate. Here we use carbonate δ18O and δ13C systematics, combined with analyses of rock and fluid inclusion mineralogy and geochemistry, to investigate the alteration of the exhumed Eocene Cycladic subduction complex on the Syros and Tinos islands, Greece. We find that in marble rocks adjacent to two fluid conduits that were active during subduction, the abundance of calcium carbonate drastically decreases approaching the conduits, whereas silicate minerals increase. Up to 60-90% of the CO2 was released from the rocks - far greater than expected via simple devolatilization reactions. The δ18O of the carbonate minerals is 5-10‰ lighter than is typical for metamorphosed carbonate rocks, implying that isotopically light oxygen was transported by fluid infiltration from the surroundings. We suggest that fluid-mediated carbonate mineral removal, accompanied by silicate mineral precipitation, provides a mechanism for the release of enormous amounts of CO2 from subduction zones. © 2014 Macmillan Publishers Limited. Source
Feinberg J.A.,Rutgers University |
Newman C.E.,Louisiana State University |
Watkins-Colwell G.J.,Yale Peabody Museum of Natural History |
Schlesinger M.D.,Albany State University |
And 4 more authors.
PLoS ONE | Year: 2014
We describe a new cryptic species of leopard frog from the New York City metropolitan area and surrounding coastal regions. This species is morphologically similar to two largely parapatric eastern congeners, Rana sphenocephala and R. pipiens. We primarily use bioacoustic and molecular data to characterize the new species, but also examine other lines of evidence. This discovery is unexpected in one of the largest and most densely populated urban parts of the world. It also demonstrates that new vertebrate species can still be found periodically even in well-studied locales rarely associated with undocumented biodiversity. The new species typically occurs in expansive open-canopied wetlands interspersed with upland patches, but centuries of loss and impact to these habitats give some cause for conservation concern. Other concerns include regional extirpations, fragmented extant populations, and a restricted overall geographic distribution. We assign a type locality within New York City and report a narrow and largely coastal lowland distribution from central Connecticut to northern New Jersey (based on genetic data) and south to North Carolina (based on call data). Copyright: © 2014 Varanda et al. Source
The Tully monster likely used its long tail to propel it forward in the water. More In 1958, amateur fossil collector Francis Tully found a prehistoric creature so strange that even scientists called it a monster. The beast has perplexed researchers ever since, with some calling the so-called "Tully monster" a worm and others classifying it as a shell-less snail. But now, an analysis of more than 1,200 Tully monster (Tullimonstrum gregarium) fossils has uncovered the monster's true identity. It's a 307-million-year-old jawless fish, a creature in the lineage leading to modern-day lampreys, the researchers found. "It's a very unusual animal," study co-author Scott Lidgard, curator of invertebrate paleontology at the Field Museum of Natural History in Chicago, told Live Science. [See Images of the Bizarre Tully Monster] The roughly foot-long (0.3 meters) monster had a narrow body with eyes like a hammerhead's on the top of its head and a long, slender snout ending in a toothy jaw. Scientists formally described it in 1966, and in 1989, Illinois designated it as the official state fossil. But experts still couldn't make heads or tails of it. They couldn't even place it in a phylum, a big-picture category that includes about 30 broad subcategories, and explains the origins of almost every living thing on Earth. Researchers have found thousands of Tully monster specimens in Illinois over the years. Many of them were digitally scanned into The Field Museum's electronic database, so scientists had plenty of samples to examine while undertaking the new study. "Basically, nobody knew what it was,” study co-author Derek Briggs, a professor of geology and geophysics at Yale University and a curator of invertebrate paleontology at the Yale Peabody Museum of Natural History, said in a statement. "The fossils are not easy to interpret, and they vary quite a bit. Some people thought it might be this bizarre, swimming mollusk. We decided to throw every possible analytical technique at it." The researchers combed through the database and also used synchrotron elemental mapping, a technique that uses a powerful light source to determine the chemistry within a fossil. Although soft-bodied, the Tully monster is a vertebrate that likely used its tail to propel itself forward in the water. Moreover, analyses showed that "the monsters are related to the jawless fishes that are still around today by a unique combination of traits, including primitive gills [and] rows of teeth," Paul Mayer, The Field Museum's fossil invertebrates collections manager, said in the statement. It also has "traces of a notochord, the flexible rodlike structure along the back that's present in chordate animals — including vertebrates like us," Mayer said. The big-eyed and pointy-toothed fish was likely a predator, said study lead author Victoria McCoy, who conducted the research as a Yale graduate student and is now at the University of Leicester in the United Kingdom. However, it's unclear when the animal first developed and when it went extinct, she said. The study was published online today (March 16) in the journal Nature. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.