Bones of primitive vegetarian dinosaurs roaming in herds across Africa 135 million years ago were found in a dry Saharan lakebed rich with unidentified fossils. The 20-ton 70-foot monster is a unique species emerging in Cretaceous Africa soon after Africa split from Pangaea. Broad rivers and open forests well fed vegetarian dinosaurs. The land later became the Sahara Desert. Jobar is legends told by Tuareg nomads now inhabiting central Niger's desert where the fossils were found. Tiguidensis refers to a cliff near the excavation site. The fossil bed contains bones of several adults and juveniles roaming their fertile turf in a herd, drowning together in a sudden flood and buried millions of years. Primitive sauropods' elongated necks, tiny heads and bulky bodies are familiar denizens of today's natural history museums. Although Jobaria resembles more familiar Apatosoraus roaming Cretacious North America its neck was shorter, its head so small its brain is as big as a baseball. It should have lived 40 million years earlier.
Slow evolution indicates African dinosaurs evolving at widely different rates. Jobaria's a survivor, a relic in its own day. Some dinosaurs change a lot in a short time. Others, like Jobaria, change little over millions of years. Unlike other Cretaceous sauropods Jobaria has spoon-shaped teeth and a relatively short neck. Based on assembled skeletons, adult Jobaria reared over 30 feet like an elephant for feeding or courtship. Its proportions elephant-like, its bones supported its body when rearing. Despite enormous size Jobaria moved gracefully, its feet close under its body. Dominant species of its time in north Africa, Jobaria used its forelimb claw to fight. Its flexible neck was well adapted for nipping smaller tree branches. 110 million year old 50-ft vegetarian nigersaurus taqueti's 600 pencil-shaped teeth are typical of Cretaceous dinosaurs. The dinosaur, one of the smallest sauropods found, is named after Niger, where found, and after world famous paleontologist Philippe Taquet. Taquet began his career fossil hunting in Niger, earning fame by linking modern birds as descendants of dinosaurs. A juvenile Jobaria's ribs bore distinctive tooth marks of an attacking dinosaur. The chief carnivorous dinosaur then was 27-foot Afrovenator, discovered earlier in the same area.
Sauropod, age 135 million years.
15 ft at the hip, 40,000 pounds.
6 ft at the chest, 70 ft long. Diet: Plants.
Methane likely killed dinosaurs
Dinosaurs maybe perished in an intense gas-fueled firestorm. Impact of a giant asteroid or comet in the Gulf of Mexico unleashed vast quantities of methane setting the air ablaze. At the end of the Cretaceous period 65 million years ago huge amounts of methane generated by rotting vegetation lay trapped in sediments over 500 meters below sea level. At these depths low temperature and high pressure combine methane with water to form solid methane hydrates. Enormous quantities of methane hydrate are trapped below Earth's surface today. Countries including the U S, Germany and Japan want to exploit their potential as fossil fuels. Methane hydrate reserves sped extinction of the dinosaurs. Huge shock waves from the asteroid or comet colliding with the ocean floor would have travel round the planet, freeing vast quantities of trapped methane. Lightning bursts in the disturbed atmosphere ignited methane-rich air, setting the atmosphere on fire, contributing to dinosaurs' demise. Further evidence points to earlier disruption in late Cretaceous sediments, possibly because of methane release, at Black Ridge off Florida's coast. More recent sea floor activity suggests trapped methane periodically escapes even without asteroid strikes. Oceanographers believe a smaller late Pleistocene blowout occurred in a Gulf of Mexico area 36 x 22 km. Methane could have been released there, had it been trapped as methane hydrate. Increased preponderance of carbon-12 over carbon-13 isotopes immediately after the impact also suggests lots of methane burned. This isotopic pattern is not repeated worldwide.
Extinction recovery takes 10,000,000 years
Species gone are gone. Fossil analysis shows 10,000,000 years after a plant or animal becomes extinct before anything like it appears, confirming increasing species loss. Up to half the world's known animal and plant species could be wiped out in a century.
Patagonia, Andes Mountains eastern slopes desert
Bones of 6 specimens of maybe largest known carnivorous dinosaur, dig began in 1997
A needle-nosed, razor-toothed dinosaur more terrifying than Tyrannosaurus rex challenges theories that bigger carnivores were loners. Possibly they lived and hunted in packs. This species lived 100 million years ago, heavier and with shorter legs than T-rex of North America. Its tail and short front legs were basically useless. The dinosaur's long, narrow skull and scissorlike jaws suggested it dissected its prey while Tyrannosaur had a nutcracker skull. The 45-ft giant was bigger than the reigning carnivore king, 41-ft Giganotosaurus. T-rex was 40 ft long. This dinosaur with long snout, long skull and sharp teeth is maybe related to Giganotosaurus but is a new species and genus, making the creatures as closely related as dogs and foxes. The dinosaur is further removed from T-rex, at least as different as dogs are from cats. Researchers giving their discovery a South American Indian name, await geological evidence that could determine whether the dinosaurs really did die together. Their dying catastrophically would support the fact that carnivorous dinosaurs traveled in groups, perhaps families. In 1995 a farmer led local researchers to the Andes foothills site 640 miles southwest of Buenos Aires. The region yields many discoveries, including Giganotosaurus. There were lots of animals. They died in lots of mud and sand to get buried in and fossilized. Remains from dinosaurs ranging from half-grown to full-grown animals reveals how the species grew. Now a desert, the area was maybe a late Cretaceous forest. Carnivorous dinosaurs too much larger are unlikely. This dinosaur is close to the size limit of effective carnivores. Too large they can't hunt prey because they're too ponderous.
SubSahara Tenere Desert, central Niger
Vast Cretaceous lakebed yields Suchomimus tenerensis - souchos Greek for crocodile, tenere the name of the desert yielding rich troves of other dinosaur fossils. 100 million years ago the world of dinosaurs was filled with strange, exotic creatures including an entirely new carnivorous species with a long thin snout like a crocodile, thick legs like tree trunks, huge curved claws like meat hooks. Evidence from its teeth and stomach indicates it often ate fish and smaller plant-eating dinosaurs. From earlier discoveries it appears the creature had evolutionary relatives as far off as Egypt, England and Brazil. Souchos, apparently young, was already 36 feet long and 12 feet high at the hip, easily the size of Tyrannosaurus rex, with curved rows of teeth. Its forearm claws carried huge curved thumbs over a foot long. It could take down anything. It was the dominant predator of its time. Souchos and relatives were spinosaurids whose backs carried long, finlike sails. From fragmentary fossils found elsewhere they apparently were dominant 90 - 125 million years ago. Fossilized stomachs of dinosaurs related to Suchomimus tenerensis contained fish bones and scales apparently etched by digestive juices, as well as remains of small herbivorous dinosaurs. Souchos' sharp teeth were better piercers and graspers than slicers and slashers, as meat hooks rather than steak knives. How varied spinosaurs arose in so many different parts of the world remains a mystery. They maybe crossed land bridges when Earth's continents were joined in supercontinents.
Fossil Illuminates Continental Drift
Madagascar dinosaur linked to Argentina
Bizarre carnivorous dinosaur sheds new light on how continents split apart and drifted across Earth tens of millions of years ago. With a 30-ft body and sharp serrated teeth like a chainsaw the horned creature lived 70 million years ago, a remote cousin of Tyrannosaurus rex, closely related to other dinosaurs half a world away. The predatory reptile probably fed on long-necked vegetarian dinosaurs, sauropods, eating lush tropic lake shore plants. Its bones help explain the timing of massive continental breakups splitting Earth's land masses apart 80 - 120 million years ago. Majungatholus atopus is apparently closely related to similar dinosaur fossils found in Argentina and India. 250 million years ago Gondwanaland, a vast supercontinent covering much of the southern hemisphere, began breaking up. By 120 million years ago South America, Antarctica, India and Africa, plus Madagascar, had just barely separated in the ponderous process of continental drift, drifting farther apart for tens of millions of years. The Madagascar dinosaur's ancestors maybe crossed huge territories still linking Madagascar to South America. Antarctica then provided a land bridge between the distant regions. From fossil evidence, dinosaurs emerged 220 million years ago, ruling Earth until driven to extinction 65 million years ago. Dinosaurs arose when all the continents were united. By the time they died out the continents had split as they are today. Dinosaur evolution helps test hypotheses about the timing of the breakup. Majungatholus, the top carnivorous dinosaur 70 million years ago, is related to dinosaurs from other continents except Africa, suggesting that Africa was then an island continent.
Fossils of Oldest Dinosaur
Calf-sized ancestors of later giants
A villager in a remote, roadless Madagascar valley led scientists to a nearby hill containing fossil jawbones of what may be the 2 oldest dinosaurs known, alongside fossils of other novel animals including at least 8 primitive mammal-like reptiles whose remains point to a critical period in the early evolution of mammals and reptiles, providing new clues to middle to late Triassic evolution 230 million years ago. Teeth indicate they were long-necked prosauropods, earliest dinosaurs, 4 - 8 ft long, bipedal and quadrupedal. They used their forefeet like hands to forage on the ancient region's lush vegetation but ran swiftly on all fours to avoid predators. Their bone structure indicates they were ancestors of plant-eating dinosaurs including 36-ton Apatosaurus.
Evolutionary crossroads
Bones of reptile-like creatures in the same dig indicate they must have lived when evolution divided their lineage in 2 directions, mammals and reptiles. Madagascar, once joined to Africa, separated when ancient supercontinent Pangaea began splitting apart 250 million years ago, the beginning of the Triassic period. Today Madagascar's Morondava Basin contains a vast variety of middle to late Triassic fossils from 200 - 230 million years ago when true dinosaurs emerged, some as small as foxes and others far bigger than elephants and whales. They dominated every continent only to become extinct in a destructive spasm 65 million years ago.
Similar fossils from Argentina
Prosauropod skulls from Madagascar resemble fossils of early dinosaurs from Argentina, radioisotope dated at 227 million years old. Madagascar finds, maybe 5 million years older, await laboratory techniques unavailable at the excavation site. 3 new sites in the same region of Madagascar contain rich late Triassic and early Jurassic dinoisaur fossils. The young man leading paleontologists to the site is named Mena, Malagasy for red, the color of Madagascar's soil. At least one fossil species will be named for him.