A specimen recovered from the Natural History Museum in London's cupboard has revealed that modern lizards evolved in the Late Triassic, not the Middle Jurassic, as previously thought.
This fossilized relative of living lizards such as monitor lizards, gila monsters, and slow worms was discovered in a museum collection dating back to the 1950s, which included specimens from a quarry near Tortworth in Gloucestershire, South West England.
The technology to expose its modern features did not exist at the time.
Fossil discovery in storeroom cupboard
As a modern-type lizard, the new fossil influences all estimates of the origin of lizards and snakes, known collectively as the Squamata, as well as assumptions about their rates of evolution and even the key trigger for the group's origin.
The team, led by Dr David Whiteside of Bristol's School of Earth Sciences, has named their amazing discovery Cryptovaranoides microlanius, which means "small butcher," in honor of its jaws, which were filled with sharp-edged slicing teeth.
"I first noticed the specimen in a cupboard full of Clevosaurus fossils in the storerooms of the Natural History Museum in London, where I am a Scientific Associate," Dr Whiteside explained via ScienceDaily.
The braincase, neck vertebrae, shoulder region, presence of a median upper tooth in the front of the mouth, the way the teeth are set on a shelf in the jaws (rather than fused to the crest of the jaws), and skull architecture such as the lack of a lower temporal bar distinguish Cryptovaranoides from Rhynchocephalia.
There is only one major primitive feature that is not found in modern squamates: an opening on one side of the upper arm bone, the humerus, through which an artery and nerve pass.
Cryptovaranoides does have some other, seemingly primitive characteristics, such as a few rows of teeth on the bones of the roof of the mouth, but this has been observed in the living European glass lizard, and many snakes, such as boas and pythons, have multiple rows of large teeth in the same area.
Despite this, it has a braincase that is advanced in comparison to most living lizards, and the bone connections in the skull indicate that it was flexible.
According to co-author Professor Mike Benton, "our fossil shifts the origin and diversification of squamates back from the Middle Jurassic to the Late Triassic."
This was a period of major ecosystem restructuring on land, with the origins of new plant groups, particularly modern-type conifers, as well as new types of insects and some of the first modern groups such as turtles, crocodilians, dinosaurs, and mammals.
The picture is then completed by including the oldest modern squamates.
These new plants and animals appear to have appeared as part of a major rebuilding of life on Earth following the end-Permian mass extinction 252 million years ago, and particularly the Carnian Pluvial Episode, 232 million years ago, when climates fluctuated between wet and dry and disrupted life.
The name of the new animal, Cryptovaranoides microlanius, reflects not only the beast's hidden nature in a drawer but also its likely lifestyle, living in cracks in the limestone on small islands that existed around Bristol at the time.
The species name, which means small butcher, refers to its jaws, which were filled with sharp-edged slicing teeth, and it preyed on arthropods and small vertebrates.
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Lizards Rapidly Evolve After Introduction to Island
New research showed that Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, as per National Geographic.
According to researchers, the five-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite in just a few decades.
Five adult pairs of the reptiles were relocated from their original island home of Pod Kopiste to the tiny neighboring island of Pod Mrcaru in the south Adriatic Sea in 1971.
According to Duncan Irschick, study author and biology professor at the University of Massachusetts, Amherst, the experiment took more than 30 years to complete.
After scientists transplanted the reptiles, the Croatian War of Independence erupted, lasting until the mid-1990s.
Because of the war, the researchers were unable to return to the island, according to Irschick.
However, tourism began to reopen in 2004, allowing researchers access to the island laboratory.
According to Irschick, the new habitat once had a healthy population of lizards that were less aggressive than the new implants.
Furthermore, the new species wiped out the indigenous lizard populations, though how this happened is unknown.
Irschick explained that the transplanted lizards adapted to their new environment in ways that accelerated their physical evolution.
For example, Pod Mrcaru had an abundance of plants for the primarily insect-eating lizards to eat. However, the lizards were not designed to digest a vegetarian diet.
Researchers discovered that the lizards developed cecal valves-muscles between the large and small intestines-that slowed food digestion in fermenting chambers, allowing their bodies to process the cellulose in the vegetation into volatile fatty acids.
He claimed that the lizard's social and behavioral structure changed as a result of its rapid physical evolution.
For one thing, the abundant food sources allowed for easier reproduction and a denser population.
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