Navigation Links
Ancient fossils shed light on anatomical changes accompanying evolution of first land vertebrates
Date:7/6/2009

Durham, NC -- Cartoon depictions of the first animals to emerge from the ocean and walk on land often show a simple fish with feet, venturing from water to land. But according to Jennifer Clack, a paleontologist at the University of Cambridge who has studied the fossils of these extinct creatures for more than two decades, the earliest land vertebrates also known as tetrapods were more diverse than we could possibly imagine.

"Some looked like crocodiles, some looked like little lizards, some like moray eels, and some were snake-like," said Clack. "They occupied all sorts of niches and habitats. And they varied tremendously in size from about 10 cm long to 5 meters."

Long before mammals, birds, and even dinosaurs roamed the Earth, the first four-legged creatures made their first steps onto land, and quickly inhabited a wide range of terrestrial environments. These early land vertebrates varied considerably in size and shape, said Clack.

To understand the anatomical changes that accompanied this diversity, Clack teamed up with two biologists who work on living fishes Charles Kimmel of the University of Oregon, and Brian Sidlauskas of the National Evolutionary Synthesis Center in North Carolina.

The researchers focused on 35 early tetrapods that lived between 385 and 275 million years ago. As a proxy for body size and shape, they examined the dimensions of a number of bones in a region of the skull known as the palate. By tracing changes in the length and width of interlocking bones in this part of the skull, the researchers hoped to get a more fine-grained picture of skeleton evolution as a whole.

"I tend to think the genetic instructions for making a skeleton come from how you make individual bones first, and then how you fit those bones together as a refinement of that," said developmental biologist Charles Kimmel, who was the first author on the paper.

When they mapped the changes in bone length and width onto the tetrapod family tree, the researchers discovered that not all bones changed size at the same rate or in the same direction. This phenomenon can result in an overall reshaping from one lineage to the next, explained Sidlauskas. "Sometimes a change in size can have indirect consequences for the shape of the animal," said Sidlauskas. "When different parts of an animal's body change size at different rates over evolutionary time, that can generate changes in body shape from one species to another."

Moreover, some changes are consistent with an evolutionary quirk known as paedomorphosis, in which species retain in adulthood the youthful dimensions that their ancestors had as juveniles. "Paedomorphosis is definitely there the descendents of some groups are retaining the proportions that their juveniles had in the past," said Clack.

These results not only help explain why early tetrapods were so diverse in size and shape, but also shed light on an important chapter in the evolution of life on land the transition from fish to amphibians.

"One of the big questions at the moment is: where did modern amphibians come from?" said Clack. "One of the hypotheses is that they have evolved by paedomorphosis and miniaturization from early tetrapods. This study lends weight to that idea."


'/>"/>

Contact: Robin Ann Smith
rsmith@nescent.org
919-668-4544
National Evolutionary Synthesis Center (NESCent)
Source:Eurekalert  

Related medicine news :

1. New Discovery Shows Ancient Herb Fights Inflammation
2. Discovery in amber reveals ancient biology of termites
3. Ancient Minerals Magnesium Oil Now Available in New Zealand
4. The Healing Power of Ancient Minerals Magnesium Oil Now Available Down Under
5. Study of ancient and modern plagues finds common features
6. Elderlys restless nights helped by ancient martial art
7. Leeds medics solve an ancient riddle -- and offer new tool for diagnosis
8. Most ancient case of tuberculosis found in 500,000-year-old human; points to modern health issues
9. New Keys to the Heart Meditation CD Series Provides Sound Energy Therapy Using First Ever Recording of an Ancient Healing Instrument
10. Chocolate Craving Has Ancient Roots
11. 454 Sequencing(TM): Science Paper Describes a Novel, Highly Efficient Method of Sequencing Ancient DNA; Sequences the Mitochondria of 10 Individual Mammoths to Prove It
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Ancient fossils shed light on anatomical changes accompanying evolution of first land vertebrates
(Date:12/9/2016)... ... 2016 , ... "I had a terrible time trying to get my grandson ... if the nebulizer had a more child-friendly design, then children would be more likely ... patent-pending NEBY to avoid the need to deliver medication via a nebulizer mask. The ...
(Date:12/8/2016)... ... December 08, 2016 , ... The West Virginia Medical ... 2017. The name change aligns the entire company with its existing Quality ... quality. , “We are very proud of the achievements associated with the West ...
(Date:12/8/2016)... ... 2016 , ... After enjoying record-breaking attendance at its last ... 33rd Annual Issues & Research Conference, March 2-3, 2017, at the Westin ... is “Persistent Challenges and New Opportunities: Using Research to Accelerate the Dialogue." 2016 ...
(Date:12/8/2016)... NY (PRWEB) , ... December 08, 2016 , ... ... is pleased to announce that “Natural Language Processing–Enabled and Conventional Data Capture Methods ... in JMIR Medical Informatics . , Results of the comparative usability study ...
(Date:12/8/2016)... ... December 08, 2016 , ... ... Medication Therapy Management (MTM), adherence, and other pharmacist-delivered patient care services, has announced ... counsel and Eric Hoessel to vice president of sales. , Litsinger joined ...
Breaking Medicine News(10 mins):
(Date:12/8/2016)... Allergy Diagnostics Market: Scope and Methodology ... are used to determine the presence of allergens ... etc. in the samples by determining the presence ... report on global allergy diagnostics market, analyzes the ... report consists of an executive summary that provides ...
(Date:12/8/2016)... Research and Markets has announced the addition of the "Global ... - Forecast to 2025" report to their offering. ... , , ... a CAGR of around 3.2% from 2015 to 2025. Some of ... extracellular microelectrode arrays and intracellular microelectrodes, research in left-to-right shunt detection ...
(Date:12/8/2016)... CITY , Dec. 8, 2016 ... US patents for improving the accuracy, reproducibility and ... images in long and small bone orthopaedic applications. ... approach to creating personalized orthopaedic restorations based on ... personalized orthopaedic restorations, the company harnesses the world,s ...
Breaking Medicine Technology: