Last Dinosaurs Before Extinction

[Liese Hittson]

Ateam of scientists has discovered the youngest dinosaur preserved in the fossil record before the catastrophic meteor impact 65 million years ago. The finding indicates that dinosaurs did not go extinct prior to the impact and provides further evidence as to whether the impact was in fact the cause of their extinction.

The team is now examining other fossil specimens that appear to be buried close to the K-T boundary and expect to find more, Lyson said. He suspects that other fossils discovered in the past may have been closer to the boundary than originally thought and that the so-called three-meter gap never existed.

Other authors of the paper include Eric Sargis and Stephen Chester (Yale University); Antoine Bercovici (China University of Geosciences); Dean Pearson (Pioneer Trails Regional Museum) and Walter Joyce (University of Tbingen).

Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using this same time scale, the Earth would have formed approximately 18.5 years earlier.) Using the same scale, people (Homo sapiens) have been on earth only since December 31 (New Year's eve). The dinosaurs' long period of dominance certainly makes them unqualified successes in the history of life on Earth.

Dinosaur communities were separated by both time and geography. The 'Age of Dinosaurs' (the Mesozoic Era ) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods). Different dinosaur species lived during each of these three periods. For example, the Jurassic dinosaur Stegosaurus had already been extinct for approximately 80 million years before the...

From about 300-200 million years ago (late Paleozoic Era until the very late Triassic), the continent we now know as North America was contiguous with Africa, South America, and Europe. They all existed as a single continent called Pangea. Pangea first began to be torn apart when a three-pronged fissure grew between Africa, South America, and North America. Rifting began as magma welled up through...

No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Some scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and some consider that they in fact represent modern...

Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates. Other scientists think it unlikely that any dinosaur could have had a rapid metabolic rate. Some scientists think that very big dinosaurs could have had warm bodies because of their...

Dinosaurs lived on all of the continents. At the beginning of the age of dinosaurs (during the Triassic Period, about 230 million years ago), the continents were arranged together as a single supercontinent called Pangea. During the 165 million years of dinosaur existence this supercontinent slowly broke apart. Its pieces then spread across the globe into a nearly modern arrangement by a process...

Paleontologists don't know for certain, but perhaps a large body size protected them from most predators, helped to regulate internal body temperature, or let them reach new sources of food (some probably browsed treetops, as giraffes do today). No modern animals except whales are even close in size to the largest dinosaurs; therefore, paleontologists think that the dinosaurs' world was much...

Some fossil photos can be viewed and downloaded from the USGS Photographic Library and our Multimedia Gallery . Fossil photos can also be viewed as published plates within many online USGS publications. Visit the USGS Publications Warehouse to search for publications. The best keywords for searches are author names, such as William Cobban, Norm Silberling, and Glenn Scott. The USGS fossil...

Reston, Virginia, was founded 47 years ago & Europeans first settled in the National Capital region 403 years ago. This human footprint can't compare to the dynamic Earth history of this region, extending back as early as 1,180 million years ago and continuing today.

A trio of USGS scientists has been involved in the excavation and study of a major animal and plant fossil discovery in Snowmass Village, Colo., which provides more than 100,000 years of vegetation and climate records for the area.

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