Navigation Links
Oddest couple ever found
Date:6/21/2013

Synchrotron imaging reveals odd couple - 250 million years ago, a mammal forerunner and an amphibian shared a burrow.

Scientists from South Africa, Australia and France have discovered a world first association while scanning a 250 million year old fossilized burrow from the Karoo Basin of South Africa.

The burrow revealed two unrelated vertebrate animals nestled together and fossilized after being trapped by a flash flood event. Facing harsh climatic conditions subsequent to the Permo-Triassic (P-T) mass extinction, the amphibian Broomistega and the mammal forerunner Thrinaxodon cohabited in a burrow.

Scanning shows that the amphibian, which was suffering from broken ribs, crawled into a sleeping mammal's shelter for protection. This research suggests that short periods of dormancy, called aestivation, in addition to burrowing behavior, may have been a crucial adaptation that allowed mammal ancestors to survive the P-T extinction.

The results of this research resulted in a paper entitled Synchrotron reveals Early Triassic odd couple: injured amphibian and aestivating therapsid share burrow and that is published in the scientific journal, PLoS ONE, on Friday, 21 June 2013 at 23:00 SA Standard Time.

The international team of scientists was led by Dr Vincent Fernandez from Wits University, South Africa and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The other authors from Wits University include Prof. Bruce Rubidge (Director of the newly formed Palaeosciences Centre of Excellence at Wits), Dr Fernando Abdala and Dr Kristian Carlson. Other authors include Dr Della Collins Cook (Indiana University); Dr Adam Yates (Museum of Central Australia) and Dr. Paul Tafforeau (ESRF).

After many impressive results obtained on fossils, synchrotron imaging has led to revived interest in the studies of the numerous fossilized burrows discovered in the Karoo Basin of South Africa and dated to 250 million years ago. The first attempt to investigate one of these burrow-casts surprisingly revealed a world-first association of two unrelated animals.

The fossil was recovered from sedimentary rock strata in the Karoo Basin. It dates from 250 million years ago, at the beginning of the Triassic Period. At that time, the ecosystem was recovering from the Permo-Triassic mass extinction that wiped out most of life on Earth. In the Pangea Supercontinent context, what is now South Africa was an enclave in the southern half called Gondwana. It was the scene of pronounced climatic warming and increased seasonality marked by monsoonal rainfall. To survive this harsh environment, many animals, including mammal-like reptiles (mammal forerunners), developed a digging behavior, attested by the numerous fossilized burrow casts discovered in the Karoo Basin. These casts have long been thought to enclose fossilized remains, triggering interest from palaeontologists. Early this year, an international group of scientists started to research the contents of these burrows using X-ray synchrotron computed microtomography.

Two burrow casts were selected from the collection at Wits to be scanned using the state-of-the-art facility at the European Synchrotron Radiation Facility (ESRF). Using the unique properties of the X-ray beam which enables non-destructive probing, the scan of the first burrow started to reveal the skull of a mammal-like reptile called Thrinaxodon, an animal previously reported in another burrow.

As the scan progressed, the three-dimensional reconstruction displayed results beyond expectations: the mammal-like reptile was accompanied by an amphibian Broomistega, belonging to the extinct group of Temnospondyl.

"While discovering the results we were amazed by the quality of the images", says lead author Fernandez, "but the real excitement came when we discovered a second set of teeth completely different from that of the mammal-like reptile. It was really something else".

Besides the pristine preservation of the two skeletons, the team focused on the reasons explaining such an unusual co-habitation. Fernandez explains: "Burrow-sharing by different species exists in the modern world, but it corresponds to a specific pattern. For example, a small visitor is not going to disturb the host. A large visitor can be accepted by the host if it provides some help, like predator vigilance. But neither of these patterns corresponds to what we have discovered in this fossilized burrow".

The scientists gathered all the information to try to reconstitute the events that led to this incredible fossil aggregation, testing scenarios one after another. "It's a fascinating scientific question: what caused the association of these two organisms in the burrow? One of the more obvious possibilities is a predator-prey interaction, but we inspected both skeletons looking for tooth marks or other evidence implying predation, ultimately finding no support for one having attempted to feed on the other," says Carlson.

His colleague, Cook, adds that the consecutive broken ribs resulted from a single, massive trauma. The amphibian clearly survived the injury for some time because the fractures were healing, but it was surely quite handicapped. According to Fernandez this Broomistega is the first complete skeleton of this rare species that has been discovered. "It tells us that this individual was a juvenile and mostly aquatic at that time of its life," he says.

The scientists eventually concluded that the amphibian crawled into the burrow in response to its poor physical condition but was not evicted by the mammal-like reptile.

Numerous Thrinaxodon specimens have been found in South Africa, many of them fossilized in a curled-up position. Abdala says: "I have always been fascinated by the preservation of Thrinaxodon fossils in a curled-up position that show even tiny bones of the skeleton preserved. It's as if they were peacefully resting in shelters at the time of death".

The shelters prevented disturbance of the skeletal remains from scavengers and weathering. "We also think it might reflect a state of torpor called aestivation in response to aridity and absence of food resources," Abdala says.

Piecing all the clues together, the team finally elucidated the enigmatic association, concluding that "the mammal-like reptile, Thrinaxodon, was most probably aestivating in its burrow, a key adaptation response together with a burrowing behavior which enabled our distant ancestors to survive the most dramatic mass extinction event. This state of torpor explains why the amphibian was not chased out of the burrow," says Rubidge.

Both animals were finally entrapped in the burrow by a sudden flood and preserved together in the sediments for 250 million years.

Tafforeau says: "Thanks to the unique possibilities for high quality imaging of fossils developed during the last decade at the ESRF, these unique specimens remain untouched, protected by their mineral matrix. Who knows what kind of information we'll be able to obtain from them in the future and which would have been completely lost if the specimen had been prepared out of its burrow cast?"


'/>"/>

Contact: Erna van Wyk
erna.vanwyk@wits.ac.za
27-011-717-4023
University of the Witwatersrand
Source:Eurekalert

Related biology news :

1. For gay couples, condom decision-making and condom use varies by race
2. G protein-coupled receptor mediates the action of castor oil
3. CARE Pharmacies Joins National Association of Specialty Pharmacy (NASP) as a Founding Corporate Member
4. Study links chemicals widely found in plastics and processed food to elevated blood pressure in children and teens
5. Drugs found to both prevent and treat Alzheimers disease in mice
6. AGA Research Foundation grant furthers digestive cancer research
7. Health defects found in fish exposed to Deepwater Horizon oil spill
8. Probiotics found to reduce hepatic encephalopathy
9. Microscopic dust particles found in underground railways may pose health risk
10. Nearly half of veterans found with blast concussions might have hormone deficiencies
11. Keystone Symposia announces grant from Alfred P. Sloan Foundation
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/25/2016)...   Unisys Corporation (NYSE: UIS ) today announced ... International Airport, New York City , to help ... to enter the United States using passports ... pilot testing of the system at Dulles last year. The ... during January 2016. --> pilot testing of the ...
(Date:1/21/2016)... , January 21, 2016 ... to a new market research report "Emotion Detection and ... Others), Software Tools (Facial Expression, Voice Recognition and ... - Global forecast to 2020", published by MarketsandMarkets, ... expected to reach USD 22.65 Billion by 2020, ...
(Date:1/18/2016)... Calif. , Jan. 18, 2016  Extenua ... software that simplifies the use and access of ... and go-to-market partnership with American Cyber.  ... brings extensive experience leading transformational C4ISR and Cyber ... and integrating the latest proven technology solutions," said ...
Breaking Biology News(10 mins):
(Date:2/9/2016)... 9, 2016 BERG, a biopharmaceutical company ... approach, has announced the appointment of Jason ... Operating Officer. Haddock brings to BERG over 20 ... years in senior financial functions at pharmaceutical companies, ... organizational management. Niven R. Narain ...
(Date:2/8/2016)... , Feb. 8, 2016 /PRNewswire/ - BIOREM Inc. (TSXV: ... the top ten finalists for clean technology companies in the ... the top 10 companies listed on the TSX Venture Exchange, ... & gas, clean technology & life sciences, diversified ... equal weighting given to return on investment, market cap growth, ...
(Date:2/8/2016)... , Feb. 8, 2016  CytRx Corporation (NASDAQ: ... company specializing in oncology, today announced that it ... agreement with Hercules Technology Growth Capital, Inc. and ... million in financing. --> ... $25 million of financing under the loan and ...
(Date:2/8/2016)... , Feb. 8, 2016 Novan, Inc. today announced that ... the Board of Directors of Novan. In addition, Robert Keegan ... North Carolina . --> ... announced that it received a total of $32.8 million of net ... its private investor network originating throughout the Research Triangle area of ...
Breaking Biology Technology: