Navigation Links
Despite their heft, many dinosaurs had surprisingly tiny genomes

They might be giants, but many dinosaurs apparently had genomes no larger than that of a modern hummingbird.

So say scientists who've linked bone cell and genome size among living species and then used that new understanding to gauge the genome sizes of 31 species of extinct dinosaurs and birds, whose bone cells can be measured from the fossil record.

The researchers, at Harvard University and the University of Reading, were led by Chris Organ and Scott V. Edwards, both at Harvard. They report their findings this week in the journal Nature.

"We see distinct differences between two major lineages of dinosaurs," says Organ, a postdoctoral fellow in organismic and evolutionary biology supported by the National Institutes of Health. "The theropods -- carnivores such as Tyrannosaurus rex and Velociraptor -- had very small genomes, in the range of modern birds. Ornithischians -- which include Stegosaurus and Triceratops -- had more moderately sized genomes, akin to those of living lizards and crocodilians. We aren't sure about the genomes of the long-necked sauropods yet."

Organ and Edwards say the clear-cut dichotomy in dinosaur genomes is likely due to different amounts of repetitive and non-coding DNA in the two groups' genetic material, a factor largely responsible for variation in genome size across animal species. They estimate that active repetitive DNA might have comprised an average 12 percent of the ornithischian genome but just 8.4 percent of theropod genetic constitution.

The work indicates that the small genomes typically associated with birds -- whose genetic composition is noticeably sparer than that of other vertebrates -- evolved in dinosaurs some 230 to 250 million years ago, rather than with the emergence of modern living birds just 110 million years ago. Organ and Edwards suggest after this shrinking, theropod genomes then stabilized in size for hundreds of millions of years, a process that continues in mo dern birds.

"Our work debunks the theory that the small, repeat-poor genomes typical of birds may have co-evolved with flight as a means of conserving energy," says Edwards, professor of organismic and evolutionary biology in Harvard's Faculty of Arts and Sciences and Alexander Agassiz Professor of Zoology and curator of ornithology in Harvard's Museum of Comparative Zoology. "In fact, our work shows these streamlined genomes arose long before the first birds and flight, and can be added to the list of dinosaur traits previously thought to be found only in modern birds, including feathers, pulmonary innovations, and parental care and nesting."

Other researchers had previously determined that the sizes of various cell types, across species, tend to reflect the size of an organism's genome. Analyzing 26 living species, Organ and Edwards are the first to show that the same applies to the bone cells called osteocytes.

These cells reside in individual lacunae, small pockets inside bone tissue. This uniquely durable cellular housing allowed the scientists to look back in time at the size of 31 extinct species' genomes: By measuring lacunae in dinosaur and extinct bird specimens housed at Harvard's Museum of Comparative Zoology and at the Museum of the Rockies in Bozeman, Mont., they were able to determine just how big the various extinct species' osteocytes had been.

"These fossils let us sample species through evolutionary time," Edwards says, "providing genomic information that's often unavailable for long-extinct ancestors."


Source:Harvard University

Related biology news :

1. Despite acidity, orange juice could still be a source of foodborne disease
2. Priming embryonic stem cells to fulfill their promise
3. Protein offers way to stop microscopic parasites in their tracks
4. Flocking together: Study shows how animal groups find their way
5. Where bacteria get their genes
6. Chickadees can help humans get their bearings
7. Bacteria use hosts immune response to their competitive advantage
8. Structures of marine toxins provide insight into their effectiveness as cancer drugs
9. Beauty queens urge girls not to sacrifice their bones
10. Researchers learn how blood vessel cells cope with their pressure-packed job
11. Stem cells electric abilities might help their safe clinical use
Post Your Comments:

(Date:10/29/2015)... Oct. 29, 2015  The J. Craig Venter Institute ... "DNA Synthesis and Biosecurity: Lessons Learned and Options for ... Health and Human Services guidance for synthetic biology providers ... --> --> Synthetic ... the potential to pose unique biosecurity threats. It now ...
(Date:10/29/2015)... October 29, 2015 NXTD ... company focused on the growing mobile commerce market ... that StackCommerce, a leading marketplace to discover and ... Wocket® smart wallet on StackSocial for this holiday ... or the "Company"), a biometric authentication company focused ...
(Date:10/27/2015)... , Oct. 27, 2015 Synaptics Inc. (NASDAQ: ... today announced that Google has adopted the Synaptics ® ... controller solutions to power its newest flagship smartphones, the ... Huawei. --> --> ... Google to provide strategic collaboration in the joint development ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... ... November 25, 2015 , ... A long-standing ... Aerospace Professionals (OPBAP) has been formalized with the signing of a Memorandum of ... with OPBAP leaders Capt. Karl Minter and Capt. Albert Glenn Tuesday, November 24, ...
(Date:11/24/2015)... ... 2015 , ... The United States Golf Association (USGA) today announced Dr. Bruce ... Presented annually since 1961, the USGA Green Section Award recognizes an individual’s distinguished service ... , Clarke, of Iselin, N.J., is an extension specialist of turfgrass pathology in the ...
(Date:11/24/2015)... (PRWEB) , ... November 24, 2015 , ... ... event of the year and one of the premier annual events for pharmaceutical ... ran from 8–11 November 2015, where ISPE hosted the largest number of attendees ...
(Date:11/24/2015)... ... November 24, 2015 , ... The Academy of Model Aeronautics ... (SIG), MultiGP, also known as Multirotor Grand Prix, to represent the First–Person View (FPV) ... Many AMA members have embraced this type of racing and several new model aviation ...
Breaking Biology Technology: