Worm lizards dispersed by 'rafting' over oceans, not continental drift

March 31, 2015

Tiny, burrowing reptiles known as worm lizards became widespread long after the breakup of the continents, leading scientists to conclude that they must have dispersed by rafting across oceans soon after the extinction of the dinosaurs, rather than by continental drift as previously thought.

Scientists at the Universities of Bath, Bristol, Yale University and George Washington University used information from fossils and DNA from living species to create a molecular clock to give a more accurate timescale of when the different species split apart from each other.

The team studied fossils of worm lizards (Amphisbaenia), a type of burrowing lizards that live almost exclusively underground. The six families of worm lizards are found in five different continents, puzzling biologists as to how these creatures became so widespread.

They found that the worm lizards evolved rapidly and expanded to occupy new habitats around 65 million years ago, just after the impact of an asteroid that caused the mass extinction of around 75 per cent of living things on Earth, including the dinosaurs.

Since this event occurred after the break-up of the super-continent Pangaea, the researchers conclude that these animals could not have dispersed across the globe using land bridges.

Instead they argue that this evidence supports a theory proposed by Charles Darwin and Alfred Russell Wallace in the 19th Century that creatures crossed from continent to continent crossing land bridges or floating across oceans - in this case being carried across the oceans on floating vegetation.

Dr Nick Longrich, from the University of Bath, explained: "Continental drift clearly can't explain the patterns we're seeing. Continental breakup was about 95 million years ago, and these animals only become widespread 30 million years later.

"It seems highly improbable not only that enough of these creatures could have survived a flood clinging to the roots of a fallen tree and then travelled hundreds of miles across an ocean, but that they were able to thrive and flourish in their new continent.

"But having looked at the data, it is the only explanation for the remarkable diversity and spread of not just worm lizards, but nearly every other living thing as well.

"Once you eliminate the impossible, whatever you're left with, no matter how improbable, must be the truth."

The researchers suggest that mass extinction actually helped the survivors of the asteroid hit colonise new places and diversify because there was less competition for food from other species.

Dr Jakob Vinther, from the University of Bristol, said: "The asteroid hit would have killed most of the plants, meaning there was no new food.

"However, scavengers like worm lizards that live off dead and decaying matter were able to survive and thrive. Their tunnels would have acted like bomb shelters, allowing them to withstand the asteroid impact and without any competition for food and space, they flourished."

Their study, published in the Proceedings of the Royal Society B, describes the earliest definitive fossil evidence of worm lizards, around 100-1000 years after the asteroid hit and long after the break-up of Pangaea. The data suggest that the lizards must have travelled across the oceans at least three times: from North America to Europe, from North America to Africa and from Africa to South America.
-end-
The study was led by Dr Nick Longrich of the University of Bath, with assistance from Dr Jakob Vinther and Dr Davide Pisani of the University of Bristol, R. Alexander Pyron of George Washington University (USA), and Professor Jacques Gauthier of Yale University (USA).

University of Bristol

Related Asteroid Articles from Brightsurf:

Asteroid's scars tell stories of its past
Asteroid Bennu, which was just sampled by NASA's OSIRIS-REx mission, only recently migrated into Earth's neighborhood, according to a detailed analysis of impact marks on boulders on its surface.

Asteroid Ryugu shaken by Hayabusa2's impactor
Professor ARAKAWA Masahiko (Graduate School of Science, Kobe University, Japan) and Hayabusa2 mission members discovered more than 200 boulders, which either newly appeared or moved as a result of the artificial impact crater created by the Japanese spacecraft's Small Carry-on Impactor.

Scientists peer inside an asteroid
New findings from NASA's OSIRIS-REx mission suggest that the interior of the asteroid Bennu could be weaker and less dense than its outer layers--like a crème-filled chocolate egg flying though space.

Designing better asteroid explorers
Recent NASA missions to asteroids have used robotic explorers to gather data about the early evolution of our Solar System, planet formation, and how life may have originated on Earth.

ATLAS telescope discovers first-of-its-kind asteroid
University of Hawai'i telescope discovers extraordinary asteroid with comet-like features that has researchers puzzled.

An iron-clad asteroid
Mineralogists from Jena and Japan discover a previously unknown phenomenon in soil samples from the asteroid 'Itokawa': the surface of the celestial body is covered with tiny hair-shaped iron crystals.

Asteroid impact enriches certain elements in seawater
University of Tsukuba researchers found two processes immediately after the end-Cretaceous asteroid impact that likely supplied chalcophile elements to the ocean, i.e., impact heating and acid rain.

Turbulent times revealed on Asteroid 4 Vesta
Planetary scientists at Curtin University have shed some light on the tumultuous early days of the largely preserved protoplanet Asteroid 4 Vesta, the second largest asteroid in our solar system.

In death of dinosaurs, it was all about the asteroid -- not volcanoes
Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers.

Active asteroid unveils fireball identity
At around 1 a.m. local standard time on April 29, 2017, a fireball flew over Kyoto, Japan.

Read More: Asteroid News and Asteroid Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.