Featured Research

from universities, journals, and other organizations

Unexpected Finding: Some Dinosaurs Grew Slower In Hard Times

Date:
December 19, 2005
Source:
University of Bonn
Summary:
Palaeontologists from the University of Bonn report on an intriguing diagnosis in the 16 December issue of the journal Science. A dinosaur which they have examined was apparently able to vary the speed of its growth according to the conditions obtained in its environment. Although tortoises and crocodiles also do this, plateosaurus engelhardti seems to be unique among dinosaurs, leading experts to puzzle over whether the family history of the dinosaurs will need to be rewritten.

Palaeontologists from the University of Bonn report on an intriguing diagnosis in the 16 December issue of the journal Science. A dinosaur which they have examined was apparently able to vary the speed of its growth according the conditions obtaining in its environment. Although tortoises and crocodiles also do this, plateosaurus engelhardti seems to be unique among dinosaurs, leading experts to puzzle over whether the family history of the dinosaurs will need to be rewritten.

"Basically dinosaurs grew like we do," the Bonn palaeontologist Dr. Martin Sander explains. "Each age corresponded to a particular body size." There was not much leeway involved. Reptiles do things differently: when food is scarce they grow more slowly than when there is food galore. Thus, a tortoise can be 30, 40 or even 60 centimetres long at the same age. "Warm-blooded animals, by contrast, cannot so easily turn down their metabolism," the lecturer says. "If the food supply is inadequate, there's only one thing they can do -- die."

Dinosaurs lie somewhere in between: although they are descended from the reptiles, many of them had become warm-blooded, most researchers today agree. And they all grew like modern mammals: in accordance with a genetically programmed blueprint and in addition relatively fast. "At least that's what was thought until recently," Dr. Sander says. "However, our findings have thrown this conception into disarray, at least for one dinosaur."

The Swabian lindworm

The dinosaur involved is plateosaurus engelhardti, the most important 'German' dinosaur, to judge from the number of fossil finds. The 'Swabian lindworm' (the finds are mainly located in Swabia, in South-West Germany) lived about 200 million years ago and was the first really big dinosaur. It grew up to 10 metres long and weighed several tons. It belonged to the group of the prosauropods, from which the giant dinosaurs later evolved. Martin Sander and his assistant Nicole Klein have subjected the plateosaur's bones to careful scrutiny. The growth of dinosaurs' bones was characterised by temporary interruptions, so that 'annual growth rings' can be detected under the microscope, rather like the growth rings of trees.

Annual rings in the bones

When growth is fast, the distance between the rings is greater. The bone tissue is then permeated with numerous longish cavities. "However, in many animals, at least at times, the annual rings were markedly closer together," Dr. Sander continues. "In these phases the dinosaurs seem to have only grown slowly." From the bone structure experts can also detect when the animals reached their full size: "Some had reached their maximum size at 12 years old, others were still growing at 27 -- we did not investigate finds of older animals." The smallest plateosaur was only 4.8 metres when fully grown -- a veritable dwarf. Others were more than twice as long.

What is above all astonishing is that all the other dinosaurs seemed to show very steady growth. This is not only true of the plateosaur's closest relations, but also of dinosaurs which came onto the evolutionary stage well before plateosaurs and which therefore could perhaps be assumed to have shown a more 'reptilian' type of growth. "These findings are puzzling," Martin Sander admits. "Of course the plateosaur may simply be an exception. However, we do not see this hypothesis as being very likely. Perhaps the extant finds have not been correctly interpreted. Or the dinosaurs' family tree as we imagine it is simply not accurate."



Story Source:

The above story is based on materials provided by University of Bonn. Note: Materials may be edited for content and length.


Cite This Page:

University of Bonn. "Unexpected Finding: Some Dinosaurs Grew Slower In Hard Times." ScienceDaily. ScienceDaily, 19 December 2005. <www.sciencedaily.com/releases/2005/12/051219084817.htm>.
University of Bonn. (2005, December 19). Unexpected Finding: Some Dinosaurs Grew Slower In Hard Times. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2005/12/051219084817.htm
University of Bonn. "Unexpected Finding: Some Dinosaurs Grew Slower In Hard Times." ScienceDaily. www.sciencedaily.com/releases/2005/12/051219084817.htm (accessed September 16, 2014).

Share This



More Fossils & Ruins News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) — Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Museum Traces Fragments of Star-Spangled Banner

Museum Traces Fragments of Star-Spangled Banner

AP (Sep. 12, 2014) — As the Star-Spangled Banner celebrates its bicentennial, Smithsonian curators are still uncovering fragments of the original flag that inspired Francis Scott Key's poem. (Sept. 12) Video provided by AP
Powered by NewsLook.com
Spinosaurus Could Be First Semi-Aquatic Dinosaur

Spinosaurus Could Be First Semi-Aquatic Dinosaur

Newsy (Sep. 11, 2014) — New research has shown that the Spinosaurus, the largest carnivorous dinosaur, might have been just as well suited for life in the water as on land. Video provided by Newsy
Powered by NewsLook.com
Meet Spinosaurus, the First-Known Water Dinosaur

Meet Spinosaurus, the First-Known Water Dinosaur

AFP (Sep. 11, 2014) — Spinosaurus aegyptiacus was adapted for both land and water, and an exhibit featuring a life-sized model, based on new fossils unearthed in eastern Morocco, opens at the National Geographic Museum in Washington on Friday. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

      Technology News



      Save/Print:
      Share:  

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile iPhone Android Web
      Follow Facebook Twitter Google+
      Subscribe RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins