Tiniest dinosaur eggs reportedly found
July 2, 2005
Special to World Science
Scientists say they have found the smallest dinosaur eggs ever—not counting bird eggs, which could be considered dinosaur eggs since scientists believe birds are living dinosaurs.
The four eggs, two of which contain remains of embryos, come from a dinosaur that may also turn out to be the smallest known, the researchers said: it may have been about the size of a goldfinch.
The eggs are about 18 millimeters (0.7 inch) long, roughly the width of a thumbnail. This makes them, too, about as big as goldfinch eggs, said Eric Buffetaut of the National Center for Scientific Research in Paris, one of the discoverers.
It’s impossible to accurately estimate the size of an adult from the size of an egg, he added, “but in birds there is nevertheless a link between egg size and adult size, with a few exceptions. What this means is that the eggs are certainly from a very small dinosaur.” A goldfinch is about 11 centimeters (a bit over 4 inches) long.
The eggs come from a theropod dinosaur, a type of dinosaur that included the famous Tyrannosaurus Rex and is also believed to be the group from which birds descend. Indeed, the newfound eggs seem to come from a sort of tiny dinosaur-bird who lived at the cusp of the transition between the two forms, Buffetaut said.
“The eggshell shows a mixture of dinosaur-like features (knobs on the surface) and bird-like characters (three structural layers),” wrote Buffetaut in the email. “These eggs are from an animal that was somewhere along the transition from dinosaurs to birds, and where exactly it should be placed is still unclear.”
The beast who laid the egg may have been “a bird-like small theropod, similar perhaps to some of the feathered dinosaurs described from rocks of comparable age in northeastern China,” but smaller, Buffetaut wrote.
These Chinese fossils include the smallest dinosaur known to date, Microraptor zhaoianus, Buffetaut added. Microraptor was about the size of a crow.
Because scientists in the past few years have come to view birds as modern-day dinosaurs, they use the term “non-avian dinosaur” rather than simply “dinosaur” to refer to the large, land-based animals that most people traditionally think of as dinosaurs.
The tiny eggs were found among a group of bones of other animals in 2002 and 2003 in an outcrop of red rocks in Phu Phok, northeastern Thailand, according Buffetaut and his colleagues. They described the eggs in the September 13 issue of the German scientific journal Naturwissenschaften (Natural Sciences).
The eggs were dated to the early Cretaceous, a period spanning from about 145 million to 100 million years ago. The non-avian dinosaurs died out much later, about 65 million years ago.
The eggs’ small size also lends further support to the theory, Buffetaut said, that dinosaurs evolved into birds. Most biologists believe this by now but skeptics remain.
“These eggs have undergone crushing, but two of them are sufficiently well preserved to assess their original size and shape,” the group wrote. Their shape was oval, like that of bird eggs, rather than the more round or blimp-like shapes characteristic of most non-avian dinosaur eggs.
The embryonic remains consisted of delicate bones that were mostly out of place and hard to identify. Analysis of them continues, Buffetaut said.
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