Featured Research

from universities, journals, and other organizations

Geologists Find First Clue To Tyrannosaurus Rex Gender In Bone Tissue

Date:
June 3, 2005
Source:
North Carolina State University
Summary:
Paleontologists at North Carolina State University have determined that a 68 million year-old Tyrannosaurus Rex fossil from Montana is that of a young female, and that she was producing eggs when she died.

Tissue within T. rex bone led to a determination of the dinosaur's gender.
Credit: North Carolina State University

It’s a girl … and she’s pregnant!

Paleontologists at North Carolina State University have determined that a 68 million year-old Tyrannosaurus Rex fossil from Montana is that of a young female, and that she was producing eggs when she died.

The proof, they say, is in the bones.

In a case of a literal “lucky break,” the scientists discovered unusual bone tissue lining the hollow cavity of the T. rex’s broken leg bone. In a paper published in the June 3 issue of the journal Science, Dr. Mary Schweitzer, assistant professor of paleontology with a joint appointment at the N.C. Museum of Natural Sciences, and her technician, Jennifer Wittmeyer, along with colleagues at Montana State University, share their findings and say that the presence of this particular tissue provides evidence of the dinosaur’s gender and a connection between the extinct giants and living birds, specifically ostriches and emus.

Schweitzer believes that the unusual tissue inside the T. rex bone is actually medullary bone: a thin layer of highly vascular bone that is found in present-day female birds only during ovulation. This estrogen-linked reproductive bone tissue is laid down inside the hollow leg bones of the birds and persists until the last egg is laid, at which time it is completely resorbed into the bird’s body. Its formation is triggered by an increase in estrogen levels, and the temporary tissue provides the calcium necessary to form eggshells. Medullary bone is only found in present-day female birds; no other egg-laying species – including crocodiles, the other living dinosaur relative – produces this tissue naturally.

Because the dinosaur tissues didn’t look exactly like pictures published of medullary bone in living birds like chicken and quail, Schweitzer’s team compared the tissue from the femur of the T. rex to that taken from leg bones of more primitive ratites, or flightless birds, such as ostriches and emus. These birds share more features with dinosaurs than other present-day birds. They selected an ostrich and an emu in different stages of their laying cycles, when medullary bone is present.

Schweitzer viewed the tissues under both a light and an electron microscope, and found that the dinosaur tissues were virtually identical to those of the modern birds in form, location and distribution. Demineralization – the chemical removal of a bone’s minerals in order to obtain organic material that is much easier to work with in a lab environment – of the samples revealed that the medullary bone from the ostrich and emu was virtually identical in structure, orientation and even color, with that seen in the T. rex.

Since only females produce medullary bone, its presence in the T. rex femur indicates that this fossil was a female, and probably one who died toward the end of her laying cycle. From a biological perspective, the tissue is another link between dinosaurs and living birds.

“The discovery of medullary bone in the T. rex is important because it allows us to objectively sex a dinosaur,” says Schweitzer. “It also adds to the robust support linking birds and dinosaurs and shows that their reproductive physiologies may have been similar. Hopefully we’ll be able to identify features within dinosaurs that will help us determine the gender of our other fossils, and lead to more information about their herd structure or family groups.”

The N.C. Museum of Natural Sciences will soon become the new home of the cast of the thigh bone. “We’re pleased to be able to provide a way for the public to see for themselves evidence that after millions of years, soft tissue can actually be preserved in dinosaur bone,” said Dr. Betsy M. Bennett, museum director. The cast will be placed in the museum’s Paleo Lab along with the complete story of where it was found, how it was excavated and how Schweitzer discovered the unique tissue cells in the hollow.

The research was funded by NC State, the N.C. Museum of Natural Sciences and the National Science Foundation.


Story Source:

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


Cite This Page:

North Carolina State University. "Geologists Find First Clue To Tyrannosaurus Rex Gender In Bone Tissue." ScienceDaily. ScienceDaily, 3 June 2005. <www.sciencedaily.com/releases/2005/06/050602173113.htm>.
North Carolina State University. (2005, June 3). Geologists Find First Clue To Tyrannosaurus Rex Gender In Bone Tissue. ScienceDaily. Retrieved October 22, 2014 from www.sciencedaily.com/releases/2005/06/050602173113.htm
North Carolina State University. "Geologists Find First Clue To Tyrannosaurus Rex Gender In Bone Tissue." ScienceDaily. www.sciencedaily.com/releases/2005/06/050602173113.htm (accessed October 22, 2014).

Share This



More Fossils & Ruins News

Wednesday, October 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Sunken WWII U-Boat That Fired On U.S. Convoy Found

Sunken WWII U-Boat That Fired On U.S. Convoy Found

Newsy (Oct. 22, 2014) U-576, a long-lost German U-boat the U.S. sank in 1942, has been found just 30 miles off North Carolina's coast and near the wreckage of another ship. Video provided by Newsy
Powered by NewsLook.com
Turns Out Jack The Ripper's True Identity Is Still Unknown

Turns Out Jack The Ripper's True Identity Is Still Unknown

Newsy (Oct. 20, 2014) After testing DNA from a shawl found near one of Jack the Ripper's victims, a scientist said he'd identified the killer. New reports refute the claim. Video provided by Newsy
Powered by NewsLook.com
Fish Fossil Shows First-Ever Sex Was Done Side By Side

Fish Fossil Shows First-Ever Sex Was Done Side By Side

Newsy (Oct. 19, 2014) A 380-million-year-old fish may be the first creature to have copulative sex - and it was side by side with arms linked, like square dancers. Video provided by Newsy
Powered by NewsLook.com
As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

Newsy (Oct. 19, 2014) With Sweden on the look-out for a suspected Russian sub, a lot of people are talking about the Cold War, but is it an apt comparison? Video provided by Newsy
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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