Image right: The hand print of a baby dinosaur from the nesting site in South Africa. (Images courtesy University of the Witwatersrand)

A new study, entitled Oldest known dinosaur nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus and published in the international journal Proceedings of the National Academy of Sciences, was led by Canadian palaeontologist Robert Reisz, a professor of biology at the University of Toronto at Mississauga, and co-authored by Hans-Dieter Sues of the Smithsonian’s National Museum of Natural History; Eric Roberts of James Cook University, Australia; and Adam Yates of the Bernard Price Institute for Paleontological Research.

The study reveals clutches of eggs, many with embryos, as well as tiny dinosaur footprints, providing the oldest known evidence that the hatchlings remained at the nesting site long enough to at least double in size.

The authors say the newly unearthed dinosaur nesting ground is more than 100 million years older than previously known nesting sites.

Image left: A fossil from the nesting site showing seven eggs, some with the embryos exposed.

At least 10 nests have been discovered at several levels at this site, each with up to 34 round eggs in tightly clustered clutches. The distribution of the nests in the sediments indicate that these early dinosaurs returned repeatedly (nesting site fidelity) to this site, and likely assembled in groups (colonial nesting) to lay their eggs, the oldest known evidence of such behavior in the fossil record.

The large size of the mother, at six meters in length, the small size of the eggs, about six to seven centimetrs in diameter, and the highly organized nature of the nest, suggest that the mother may have arranged them carefully after she laid them.

“The eggs, embryos, and nests come from the rocks of a nearly vertical road cut only 25 meters long,” Reisz says. “Even so, we found ten nests, suggesting that there are a lot more nests in the cliff, still covered by tons of rock. We predict that many more nests will be eroded out in time, as natural weathering processes continue.”

Image right: A nest of dinosaur eggs from the South African nesting site.

The fossils were found in sedimentary rocks from the Early Jurassic Period in the Golden Gate Highlands National Park in South Africa. This site has previously yielded the oldest known embryos belonging to Massospondylus, a relative of the giant, long-necked sauropods of the Jurassic and Cretaceous periods.

“This amazing series of 190 million year old nests gives us the first detailed look at dinosaur reproduction early in their evolutionary history, and documents the antiquity of nesting strategies that are only known much later in the dinosaur record,” says Evans.

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In a new study  in the journal Palaeontology, University of Florida and Smithsonian Tropical Research Institute scientists describe a new 20-foot extinct species discovered in the same Colombian coal mine with Titanoboa, the world’s largest snake. The findings help scientists better understand the diversity of animals that occupied the oldest known rainforest ecosystem, which had higher temperatures than today, and could be useful for understanding the impacts of a warmer climate in the future.

Image right: This illustration shows how Acherontisuchus guajiraensis, a 60-million-year-old ancestor of crocodiles, would have looked in its natural setting. Titanoboa, the world’s largest snake, is pictured in the background. (Illustration by Danielle Byerley/click to enlarge)

The 60-million-year-old freshwater relative to modern crocodiles is the first known land animal from the Paleocene New World tropics specialized for eating fish, meaning it competed with Titanoboa for food. But the giant snake could have consumed its competition, too, researchers say.

“The younger individuals were definitely not safe from Titanoboa, but the biggest of these species would have been a bit much for the 42-foot snake to handle,” said lead author Alex Hastings, a graduate student at the Florida Museum of Natural History and UF’s department of geological sciences.

Image left: University of Florida researchers unearth fossils from the 60-million-year-old Cerrejon formation in northeastern Colombia, one of the world’s largest open-pit coal mines. (Photo by Edwin Cadena)

The new species is a dyrosaurid, commonly believed to be primarily ocean-dwelling, coastal reptiles. The new adult specimens challenge previous theories the animals only would have entered freshwater environments as babies before returning to sea.

Fossils of a partial skeleton of the species, Acherontisuchus guajiraensis, show dyrosaurids were key players in northeastern Colombia and that diversity within the family evolved with environmental changes, such as an asteroid impact or the appearance of competitors from other groups, said Christopher Brochu, an associate professor of vertebrate paleontology in the department of geoscience at the University of Iowa, who was not involved in the study.

“We’re facing some serious ecological changes now,” Brochu said. “A lot of them have to do with climate and if we want to understand how living things are going to respond to changes in climate, we need to understand how they responded in the past. This really is a wonderful group for that because they managed to survive some catastrophes, but they seemed not to survive others and their diversity does seem to change along with these ecological signals.”

Image left: This photograph shows the size difference in the jawbones of two 60-million-year-old crocodile ancestors found in northeastern Colombia by University of Florida researchers.The newly described Acherontisuchus guajiraensis, top, and Cerrejonisuchus improcerus, bottom. C. improcerus was the first ancient crocodyliform found in the Cerrejon open-pit coal mine. The new species is the first known land animal from the Paleocene New World tropics specialized for eating fish. (Photo by Kristen Grace)

The species is the second ancient crocodyliform found in the Cerrejon mine of northern Colombia, one of the world’s largest open-pit coal mines. The excavations were led by study co-authors Jonathan Bloch, Florida Museum associate curator of vertebrate paleontology, and paleobotanist Carlos Jaramillo of the Smithsonian Tropical Research Institute.

“This one is related to a group that typically had these long snouts” Hastings said. “It would have had a relatively similar diet to the other (coastal) species, but surprisingly it lived in a more freshwater environment.”

The genus is named for the river Acheron from Greek mythology, “the river of woe,” since the animal lived in a wide river that emptied into the Caribbean. Unlike the first crocodile relative found in the area, which had a more generalized diet, the snout of the new species was long, narrow and full of pointed teeth, showing a specialization for hunting the lungfish and relatives of bonefish that inhabited the water.

“The general common wisdom was that ancestrally all crocodyliforms looked like a modern alligator, that all of these strange forms descended from a more generalized ancestor, but these guys are showing that sometimes one kind of specialized animal evolved from a very different specialized animal, not a generalized one,” Brochu said. “It’s really showing us a level of complexity to the history that 10 years ago was not anticipated.”

During the Paleocene in South America, the environment was dominated by reptiles, including giant snakes, turtles and crocodiles. The dyrosaurid family originated in Africa about 75 million years ago, toward the end of the age of dinosaurs, and arrived in South America by swimming across the Atlantic Ocean.

“The same thing that snuffed out the dinosaurs killed off most of the crocodiles alive at the time,” Hastings said. “The dyrosaurids are one of the few groups to survive the extinction and later become more successful.”

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Image right: Unlike other baleen whales, gray whales feed on bottom-dwelling organisms by suctioning sediments and filtering out worms and crustaceans. (Courtesy of Flip Nicklin)

The researchers, who analyzed California gray whale (Eschrichtius robustus) responses to climate change over the past 120,000 years, also found evidence to support the idea that the population of gray whales along the Pacific Coast before the arrival of humans was two to four times today’s population, which stands at about 22,000. The whale is considered a conservation success story because protections instituted as early as the 1930s have allowed populations to rebound from fewer than 1,000 individuals in the early 20th century, after less than 75 years of systematic whaling.

Image left: An 1872 illustration of a gray whale by Charles Melville Scammon.

“There almost certainly were higher gray whale populations in the past,” said evolutionary biologist David Lindberg, a UC Berkeley professor of integrative biology who coauthored the paper with his former student, Nicholas D. Pyenson, now curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History in Washington, D.C. The paper appeared in the online, open-access journal PLoS ONE.

Lindberg and Pyenson suggest that higher populations in the past were possible because gray whales utilized a greater variety of food resources – resources that today’s whales are only now beginning to exploit. According to Lindberg, gray whales were once thought to feed only by suctioning seafloor sediment and filtering out worms and amphipods – so-called benthic organisms. But some whales are now eating herring and krill as well, just like their baleen whale relatives, which include the humpback and the blue.

Image right: This 19th century drawing depicts gray whales cavorting among ice floes in the norhtern Pacific Ocean. This observation suggests that gray whales can tolerate pack ice, a trait that helped it survive ice ages. (From Scammon, 1874)

Some whales are even dropping out of the migratory rat race. One group hangs out year-round off Vancouver Island in Canada, where they chase herring and krill.

“We propose that gray whales survived the disappearance of their primary feeding ground by employing generalist filter-feeding modes, similar to the resident gray whales found between northern Washington State and Vancouver Island,” the scientists write in their paper.

“A combination of low population numbers and a species migrating between places where humans didn’t bother them gave us the impression that gray whales have a stereotypical migratory and feeding behavior that may not be historically correct,” Lindberg said.

Image left: A gray whale pushing its mouth and head above the water.

The new population numbers accord with a 2007 estimate that the California gray whale population was likely 76,000 to 120,000 before humans began hunting them. That estimate, by Stephen Palumbi of Stanford University and his collaborators, was based on an analysis of gray whale genetic diversity.

The numbers clash, however, with claims by some ecologists that populations of between 15,000 and 20,000 are likely the most that the Pacific Coast – specifically along the whales’ 11,000 kilometer (6,900 mile) migratory route from Baja California to the Bering Sea – could support, today or in the past.

“Our data say that, if the higher estimates are right, gray whales would have made it through the Ice Ages in numbers sufficiently large to avoid bottlenecking,” Pyenson said. “If gray whale populations were at the lower levels, they would only have squeaked through the ice ages with populations of hundreds or a few thousand. That would have left bottlenecking evidence in their DNA.”

Bottlenecking is when populations drop so low that inbreeding becomes common, decreasing the genetic diversity in the species and making them less able to adapt to environmental change.

Gray whales are survivors

The new assessment is good news for gray whales, which appear to have “a lot more evolutionary plasticity than anyone imagined,” Lindberg said. This could help them survive the climate change predicted within the next few centuries that is characterized by an expected sea level rise of several meters.

Image right: A gray whale calf. (Photo by Patty Geary)

“I suspect the gray whales will be among the winners in the great climate change experiment,” Pyenson said.

Lindberg and Pyenson initiated the study several years ago in the face of conflicting and contentious estimates for past gray whale populations. They thought that an understanding of how gray whales adapted to climate change over the past 3 million years, the period called the Pleistocene, might provide insight into how they will adapt to climate change today.

Since gray whales arose – the oldest fossils date from 2.5 million years ago – Earth has gone through more than 40 major cycles of warming and cooling, each of which significantly affected the world’s flora and fauna. During the last glacial cold spell, between 50,000 and 10,000 years ago, most of the large terrestrial mammals disappeared through a combination of climate change and human depredation, Lindberg noted. The marine realm, however, experienced almost no extinctions and very few new originations during that same period.

--Source: Robert Sanders, University of California, Berkeley

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Image right: Dog remains from a burial on Santa Rosa Island. (Photos courtesy Torben Rick)

In recent research on Santa Rosa Island off the coast of Southern California, isotope readings of carbon and nitrogen found in the bones of Chumash Indians and domestic dogs excavated from archaeological sites (dating from the Late Holocene–130AD-1830) show that both humans and dogs have nearly identical signatures of stable isotopes. The discovery illustrates that the Chumash and their dogs shared virtually the same diet of food from the sea—finfish, shellfish, marine mammals and sea birds. By contrast, isotope analysis of fox remains from the same period, also from Santa Rosa Island, shows the foxes ate a diet of terrestrial foods, such as insects and mice. The study was conducted by a scientific team led by Torben Rick of the Department of Anthropology at the Smithsonian’s National Museum of Natural History.

Image left: An island fox (Photo by Rene Vellanoweth, Cal State University Los Angeles)

The data show that domestic dogs and humans were living in close proximity and the dogs were either fed scraps and leftovers from human meals, or they were scavenging in kitchen middens and refuse heaps and consuming human feces. The Santa Rosa Island findings confirm what archaeologists have discovered elsewhere in North America–that the isotopic signatures of the bones of humans and their dogs are extremely similar.

Image right: Torben Rick excavating an archaeological site on Santa Rosa Island.

In some situations where the destruction of human remains for isotope analysis is objectionable or banned, the researchers say, dog remains might easily be substituted for human remains to help reveal the diets of the humans. A paper on this research “Stable isotope analysis of dog, fox and human diets at a Late Holocene Chumash village on Santa Rosa Island, California,” was recently published in the Journal of Archaeological Science.–John Barrat

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“The first evidence we have that turkeys were kept and bred by humans comes from Tehuacan in Mexico about 2000 years ago” Smith says. “By around A.D. 500 turkeys were also being raised by Native Americas in the Southwest United States, based on early evidence recovered from cave sites such as Tseahatso in Arizona’s Canyon del Muerto and the Tularosa Cave in New Mexico.”

Image right: Turkey pens at the site of Casas Grandes, Chihuahua. (Courtesy Amerind Foundation, Inc., Dragoon, Az. Photo by Tommy Carroll)

Natalie Munro, a former postdoctoral fellow in the Natural History Museum’s Program in Human Ecology and Archaeobiology, and now a professor at the University of Connecticut has recently summarized the different archaeological clues that scientists look for when trying to answer such a question.  Such evidence includes the existence of eggshells, gizzard stones, healed broken bones, the remains of turkeys outside their natural range, and evidence that turkeys consumed food raised by humans, such as corn and beans. “The most convincing evidence for domestication is turkey droppings and the presence of enclosures that served as pens,” Smith says.

Image left: The remains of a headless turkey excavated at the site of Casas Grandes, Chihuahua. Turkeys were apparently frequently sacrificed as part of dedication ceremonies for buildings and plazas at the site. (Courtesy Amerind Foundation, Inc. Photo by Alfred Cohn)

Morphological studies of turkeys recovered from Southwest prehistoric sites have classified most as belonging to the local Southwest subspecies, Merriam’s wild turkey (Meleagris gallopavo merriami).

Unlike today, the original reason for raising turkeys may not have been for food. Archaeological evidence has revealed that the original motivation for domesticating turkeys was for their feathers. The turkey’s symbolic role in historic Southwest societies is extensively documented and there are frequent references to the use of turkey feathers in ritual contexts as components of costumes, ritual regalia, prayer sticks, and isolated feather bundles.

By examining clues such as cut marks, fragmented bones, burning, and disposal of bones in trash middens, scientists have determined that raising turkeys domestically for food became widespread across the Southwest after A.D. 900. It took another 900 years, however, for the turkey to find its way to the Thanksgiving dinner table as a holiday staple.–Johnny Gibbons

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A 48 million-year-old fossilized leaf has revealed the oldest known evidence of a macabre part of nature – parasites taking control of their hosts to turn them into zombies.

The discovery has been made by a research team led by David Hughes of the University of Exeter in England, who studies parasites that can take over the minds of their hosts; Conrad Labandeira from the Smithsonian’s National Museum of Natural History; and  Torsten Wappler, from the Steinmann Institute in Germany.

Image right: An ant killed by a fungal parasite is shown here biting into a leaf vein. The fungal growth can be clearly seen issuing from the ant’s head. (Photo by David P. Hughes)

All manner of animals are susceptible to the often deadly body invasion, but scientists have been trying to track down when and where such parasites evolved.

“There are various techniques, called a molecular clock approach, which we can use to estimate where and when they developed and fossils are an important source of information to calibrate such clocks,” Hughes says.

“This leaf shows clear signs of one well documented form of zombie-parasite, a fungus which infects ants and then manipulates their behavior.”

The fungus, called Ophiocordyceps unilateralis, appears to take over the mind of infected ants – causing them to leave their colonies and head for a leaf which provides the ideal conditions for the parasite to reproduce.

Image left and below: This 48-million-year-old leaf fossil from Messel clearly bears the tell-tale scars of ants that have been infected with the mind-controlling fungal parasite. (Photo by Torsten Wappler)

When the ant gets there it goes into a ‘death grip’– biting down very hard on the major vein of a leaf. This means that when the ant dies, its body stays put so the fungus has time to grow and release its spores to infect other ants.

The death grip bite leaves a very distinct scar on the leaves. This prompted Hughes, Labandeira and Wappler to search for potential evidence of the fungus at work by studying the fossilized remains of leaves.

After studying leaf fossils from the Messel Pit, a site on the eastern side of the Rhine Rift Valley in Hesse, Germany, they found clear evidence of the death grip bite in a 48 million-year-old leaf specimen.

“The evidence we found mirrors very closely the type of leaf scars that we find today, showing that the parasite has been working in the same way for a very long time,” Hughes explains.

“This is, as far as we know, the oldest evidence of parasites manipulating the behaviour of their hosts and it shows this parasitic association with ants is relatively ancient and not a recent development.

“Hopefully we can now find more fossilised evidence of parasitic manipulation. This will help us shed further light on the origins of this association so we can get a better idea of how it has evolved and spread.”

The paper, Ancient death-grip leaf scars reveal ant-fungal parasitism, was published in a recent edition of Royal Society journal Biology Letters. –Research News, University of Exeter

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Image right: The highest coastal mountain range in the world, the Sierra Nevada de Santa Marta is visible in this east-southeast-looking view. (Image Science and Analysis Laboratory, NASA-Johnson Space Center)

The study, published in the Journal of South American Earth Sciences, involved state-of-the-art geological, structural, palaeomagnetic, geochemical and geochronological analysis conducted by collaborators from several universities and research institutions, including the Smithsonian Tropical Research Institute in Panama. Smithsonian scientists were part of the study’s four-year examination of Santa Marta’s geological evolution.

The two highest peaks in the Santa Marta Range are Cristobal Colon Peak, which rises 19,029 feet above sea level, and Simon Bolivar Peak, which is 18,947 feet above sea level. The diverse rock record exposed in Santa Marta rests on an ancient foundation that is more than 1 billion years old and is linked, the researchers determined, to other old massifs in the Americas. Using the ancient magnetic field recorded in these rocks, the Smithsonian research group revealed Santa Marta’s 1,367-mile journey from northern Peru to its modern position on the Caribbean coast of Colombia during the past 170 million years.

Image right: Sierra Nevada de Santa Marta

Sophisticated laboratory analyses of Santa Marta rock samples also offered an explanation of their origin as remnants of extinct volcanoes and mountains that once existed but were later obliterated by powerful geologic forces.

“This integrated study represents a long-awaited contribution—particularly  to the international scientific community who work in the circum-Caribbean—and fills a gap in the picture of the region’s geology,” said Agustin Cardona, post doctoral fellow at the Smithsonian Tropical Research Institute.

Other aspects of the study revealed recent dislocations along the Sierra’s bounding faults—evidence of historic earthquakes and a large submarine canyon carved in the floor of the Caribbean Sea.

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Image right: A pre-Columbian raised field in French Guiana filled with small, round mounds for growing crops.

Centuries ago these natives grew maize, manioc and squash upon a matrix of raised beds in flat, regularly flooded coastal marshes. Scooping slices of topsoil from the marsh they flipped them together and upside down, creating mounds which they topped with soil from other areas. Crops were planted, tended and harvested on this matrix of small islands.

Using aerial photographs, researchers have recently located a number of long abandoned “fossil” agricultural fields used by the Arauquinoid in coastal French Guiana. Follow-up examination of the soil and associated fragments from cooking implements, done in part by scientists at the Smithsonian Tropical Research Institute in Panama, have revealed microscopic starch grains from corn and manioc.  Squash phytoliths also were recovered from soil analysis.

Image left: The aerial photograph at top shows different types of raised fields in a complex in French Guiana. The bottom image is an interpretation of  these earthworks based on stereoscopic ananlysis and field studies.

This new research has revealed that in areas considered unsuitable for farming today, “pre-Columbian farmers constructed thousands of raised fields in the seasonally flooded coastal savannas of the Guianas,” scientists write in a paper published recently in the Proceedings of the National Academy of Sciences. ”They built conspiciuous earthworks, including raised fields, canals and ponds, that enabled them to practice intensive permanent agriculture in this low-lying region with highly seasonal rainfall.”  The study combined archeology, archeobotany, paleoecology, soil science, ecology and aerial imagery and was carried out by scientists from a number of organization, including the University of Bayreuth in Germany, the University of Montpellier II and Centre d’Ecologie Fonctionnelle et Evolutive in France, the University of Exeter, and the Smithsonian Tropical Research Institute in Panama.

Image right: A matrix of raised mounds in an abandon field in a part of French Guiana named Savane Grande Macoua. Only the mounds are above water level.

In a region that receives on average four meters of rain each year, scientists were puzzled why the mounds have not eroded into obscurity over the centuries. They discovered that ants and termites, living in the raised mounds since before they were abandoned by the Arauquinoid, have continually rebuilt them with large quantities of new organic matter. Earthworms, attracted to this rich soil, kept the mounds porous, allowing rain to percolate through without washing them away. Grasses and other plants keep the mounds stable. A survey of the ants and termites in these former agricultural swamps, revealed that their nests occur entirely on the mounds, with none in the low, often submerged, areas surround them.

Researchers now speculate that as the fertility of the mounds decreased with continued crop growing, these ancient farmers may have let their mound-matrix fields lay fallow, allowing ants, termites and worms to replenish the soil’s nutrients. This largely forgotten practice of growing crops in marshes and allowing ecological engineers such as ants and termites to replenish nutrients is a technique that may have practical uses in modern sustainable farms, the researchers write.

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