Fossils of dinosaur-era crocodiles found in Sahara
Five exotic crocodiles that lived alongside the dinosaurs 100 million years ago, including one sporting boar-like tusks and another with a duckbill snout, have been discovered in the Sahara.
Dinosaur Era Crocodile Fossil
Unlike their modern cousins, the ancient crocodilians were as agile on land as they were in the water.
They were reptiles like the dinosaurs, but belonged to a completely separate lineage that continues to this day.
The crocodiles once ran and swam across present-day Niger and Morocco, when the region was covered by lush plains and broad rivers.
Scientists found the newly-identified fossils at a number of sites in the Sahara desert. Many were uncovered at one location, lying on the surface of a remote and windswept stretch of rock and dunes.
Expedition leader Professor Paul Sereno, from the University of Chicago, has previously described the largest find, Sarcosuchus imperator, which measured 40 feet and weighed eight tons.
Popularly known as ”SuperCroc”, the giant carnivore was the biggest but not the strangest of the extinct creatures.
They were given nicknames by the scientists, based on their unusual physical features.
”BoarCroc” (Kaprosuchus saharicus): A 20 feet upright meat-eater with an armoured snout and three sets of dagger-shaped fangs.
”RatCroc” (Araripesuchus rattoides): Discovered in Morocco, this was a three-foot-long upright plant and grub-eater. It had a pair of lower jaw buckteeth which were used to dig for food.
”PancakeCroc” (Laganosuchus thaumastos): This animal’s fossils were found in Niger and Morocco. It was a 20-foot-long squat fish-eater with a three-foot-long pancake-flat head and spiky teeth on slender jaws.
”DuckCroc” (Anatosuchus minor): A three-foot upright species that ate fish, frogs and grubs. It had a broad, overhanging snout and a long nose. Sensory areas on the snout helped it root around shallow waters for prey.
”DogCroc” (Araripesuchus wegeneri): Fossils found in Niger included five skeletons next to each other on a single block of rock. DogCroc was a three-foot-long upright plant and grub eater with a soft, doglike forward-pointing nose.
Describing the finds in National Geographic Magazine, Prof Sereno wrote: ”My African crocs appeared to have had both upright, agile legs for bounding overland and a versatile tail for paddling in water.
”Their amphibious talents in the past may be the key to understanding how they flourished in, and ultimately survived, the dinosaur era.”
Colleague Dr Hans Larsson, from McGill University in Montreal, Canada, who discovered the bones of BoarCroc and PancakeCroc, said: ”We were surprised to find so many species from the same time in the same place.
”Each of the crocs apparently had different diets, different behaviours. It appears they had divided up the ecosystem, each species taking advantage of it in its own way.”
The scientists studied the animals’ brains by creating digital and physical casts from CT-scans, 3D X-rays.
Both DogCroc and DuckCroc had broad, spade-shaped forebrains that looked different from those of living crocodiles.
”They may have had slightly more sophisticated brain function than living crocs, because active hunting on land usually requires more brain power than merely waiting for prey to show up,” said Dr Larsson.
A paper on the finds is to appear in the journal ZooKeys. The creatures will also star in a documentary, ”When Crocs Ate Dinosaurs”, to be shown on the National Geographic Channel.
Source: telegraph.co.uk
Central Africa’s Tropical Congo Basin Was Arid, Treeless In Late Jurassic
The Congo Basin — with its massive, lush tropical rain forest — was far different 150 million to 200 million years ago. At that time Africa and South America were part of the single continent Gondwana. The Congo Basin was arid, with a small amount of seasonal rainfall, and few bushes or trees populated the landscape, according to a new geochemical analysis of rare ancient soils.
The geochemical analysis provides new data for the Jurassic period, when very little is known about Central Africa’s paleoclimate, says Timothy S. Myers, a paleontology doctoral student in the Roy M. Huffington Department of Earth Sciences at Southern Methodist University in Dallas.
“There aren’t a whole lot of terrestrial deposits from that time period preserved in Central Africa,” Myers says. “Scientists have been looking at Africa’s paleoclimate for some time, but data from this time period is unique.”
There are several reasons for the scarcity of deposits: Ongoing armed conflict makes it difficult and challenging to retrieve them; and the thick vegetation, a humid climate and continual erosion prevent the preservation of ancient deposits, which would safeguard clues to Africa’s paleoclimate.
Myers’ research is based on a core sample drilled by a syndicate interested in the oil and mineral deposits in the Congo Basin. Myers accessed the sample — drilled from a depth of more than 2 kilometers — from the Royal Museum for Central Africa in Tervuren, Belgium, where it is housed. With the permission of the museum, he analyzed pieces of the core at the SMU Huffington Department of Earth Sciences Isotope Laboratory.
“I would love to look at an outcrop in the Congo,” Myers says, “but I was happy to be able to do this.”
The Samba borehole, as it’s known, was drilled near the center of the Congo Basin. The Congo Basin today is a closed canopy tropical forest — the world’s second largest after the Amazon. It’s home to elephants, great apes, many species of birds and mammals, as well as the Congo River. Myers’ results are consistent with data from other low paleolatitude, continental, Upper Jurassic deposits in Africa and with regional projections of paleoclimate generated by general circulation models, he says.
“It provides a good context for the vertebrate fossils found in Central Africa,” Myers says. “At times, any indications of the paleoclimate are listed as an afterthought, because climate is more abstract. But it’s important because it yields data about the ecological conditions. Climate determines the plant communities, and not just how many, but also the diversity of plants.”
While there was no evidence of terrestrial vertebrates in the deposits that Myers studied, dinosaurs were present in Africa at the same time. Their fossils appear in places that were once closer to the coast, he says, and probably wetter and more hospitable.
The Belgium samples yielded good evidence of the paleoclimate. Myers found minerals indicative of an extremely arid climate typical of a marshy, saline environment. With the Congo Basin at the center of Gondwana, humid marine air from the coasts would have lost much of its moisture content by the time it reached the interior of the massive continent.
“There probably wouldn’t have been a whole lot of trees; more scrubby kinds of plants,” Myers says.
The clay minerals that form in soils have an isotopic composition related to that of the local rainfall and shallow groundwater. The difference in isotopic composition between these waters and the clay minerals is a function of surface temperature, he says. By measuring the oxygen and hydrogen isotopic values of the clays in the soils, researchers can estimate the temperature at which the clays formed.
Myers presented his research, “Late Jurassic Paleoclimate of Central Africa,” at a scientific session of the 2009 annual meeting of The Geological Society of America in Portland, Ore., Oct. 18-21.
The research was funded by the Roy M. Huffington Department of Earth Sciences at SMU, and the Institute for the Study of Earth and Man at SMU.
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What are Fossils
Fossils (from Latin fossus, literally “having been dug up”) are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa (phylogeny) are some of the most important functions of the science of paleontology. Such a preserved specimen is called a “fossil” if it is older than some minimum age, most often the arbitrary date of 10,000 years ago. Hence, fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archaean Eon several billion years old. The observations that certain fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century. The development of radiometric dating techniques in the early 20th century allowed geologists to determine the numerical or “absolute” age of the various strata and thereby the included fossils.
Like extant organisms, fossils vary in size from microscopic, such as single bacterial cells only one micrometer in diameter, to gigantic, such as dinosaurs and trees many meters long and weighing many tons. A fossil normally preserves only a portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous exoskeletons of invertebrates. Preservation of soft tissues is rare in the fossil record. Fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces (coprolites) of a reptile. These types of fossil are called trace fossils (or ichnofossils), as opposed to body fossils. Finally, past life leaves some markers that cannot be seen but can be detected in the form of biochemical signals; these are known as chemofossils or biomarkers.