Dinosaurs had pregnancies as early as age 8, far before they reached their maximum adult size, a new study finds.
Researchers at Ohio University and University of California at Berkeley have found medullary bone – the same tissue that allows birds to develop eggshells – in two new dinosaur specimens: the meat-eater Allosaurus and the plant-eater Tenontosaurus. It’s also been found in Tyrannosaurus rex.
The discovery allowed researchers to pinpoint the age of these pregnant dinosaurs, which were 8, 10 and 18. That suggests that the creatures reached sexual maturity earlier than previously thought, according to the scientists, who will publish their study Jan. 15 in the journal Proceedings of the National Academy of Sciences.
The scientists originally studied the bones, which come from different geologic periods, to learn more about dinosaur growth rates. Because researchers rarely find fossils of adult dinosaurs, some have speculated that the ancient beasts never stopped developing, said Andrew Lee, a postdoctoral student at the Ohio University College of Osteopathic Medicine who conducted the work as a graduate student at University of California at Berkeley with scientist Sarah Werning.
The new study suggests another explanation: Dinosaurs grew fast but only lived three to four years in adulthood. Offspring were probably precocious, like calves or foals, Lee said.
“We were lucky to find these female fossils,” Werning said. “Medullary bone is only around for three to four weeks in females who are reproductively mature, so you’d have to cut up a lot of dinosaur bones to have a good chance of finding this.”
The research also offers more evidence that dinosaurs were less like reptiles and more like birds. Though dinosaurs had offspring before adulthood, their early sexual maturity was more a function of their tremendous size than any anatomical similarity to crocodiles.
When they factored in the size of the dinosaurs, Lee and Werning found that the reptile model for sexual maturity predicted that the ancient beasts would have had offspring as late as age 218. “That’s clearly ridiculous,” Lee said. Research shows that most dinosaurs only lived until age 30, though long-necked creatures such as Brontosaurus may have reached 60.
“We hope this is the last nail in the coffin, but some scientists still cling to the notion that dinosaurs weren’t like birds,” Lee said.
The discovery also sheds new light on the evolution of birds. The presence of medullary tissue in these dinosaurs, which lived as long as 200 million years ago, shows that the reproductive strategies of modern birds have ancient origins.
Because birds have evolved to be much smaller than dinosaurs, however, their reproductive strategies and growth spans now bear no resemblance to those of T. rex. Birds grow to adulthood in only 40 days, but may take one to 10 years to reach sexual maturity. That’s relatively similar in other tiny critters such as shrews, Lee said.
Andrea Gibson | EurekAlert!
Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth
Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
25.07.2017 | Physics and Astronomy
25.07.2017 | Earth Sciences
25.07.2017 | Life Sciences