Researchers discover overlooked Jurassic Park of lizards
Date:
May 3, 2022
Source:
University of Bristol
Summary:
New research moves back the moment of the radiation of squamates
-- the group of reptiles that includes lizards, snakes and worm
lizards -- to the Jurassic, a long time before current estimates.
FULL STORY ==========================================================================
New research published today in eLife by researchers from the Institut
Catala` de Paleontologia Miquel Crusafont (ICP) and the University of
Bristol (UB) moves back the moment of the radiation of squamates --
the group of reptiles that includes lizards, snakes and worm lizards --
to the Jurassic, a long time before current estimates.
==========================================================================
The Squamata is the largest order of reptiles, including lizards, snakes
and worm lizards. Squamates are all cold-blooded, and their skins are
covered by horny scales. They are key parts of modern terrestrial faunas, especially in warmer climates, with an astonishing diversity of more
than 10,000 species.
However, understanding the evolutionary paths that forged their success
are still poorly understood.
There is consensus that all the main squamate groups had arisen before
the event that wiped out dinosaurs and other groups of reptiles at
the end of the Mesozoic era. Before that global catastrophic event,
through the Cretaceous, many terrestrial tetrapod groups like mammals,
lizards and birds, apparently underwent a great diversification during
the so-called Cretaceous Terrestrial Revolution, triggered by the rise
of flowering plants. The scarcity of fossil remains of squamates through
the Jurassic suggested that the main burst of squamate evolution happened
in the Cretaceous (between 145 and 66 Myr.), when their fossil record dramatically improves.
Now, a new paper published in eLife, led by Arnau Bolet, paleontologist
at the Institut Catala` de Paleontologia Miquel Crusafont and the
University of Bristol, however, challenges this view by suggesting
a much earlier radiation of squamates. Along with colleagues from the University of Bristol Michael Benton, Tom Stubbs and Jorge Herrera-Flores, their research concludes that this group of reptiles probably achieved a diverse array of adaptations in the Jurassic (between 201 and 145 Myr.),
long before previously thought. "Even though Jurassic squamates are rare, reconstructed evolutionary trees show that all the main specializations
of squamates evolved then, and it's possible to distinguish adaptations
of geckoes, iguanas, skinks, worm lizards, and snakes some 50 million
years earlier than had been thought," explains Michael Benton, co-author
of the research.
But how could the scarce Jurassic fossils suggest an early burst in
evolution? The key is in their anatomy. The few Jurassic squamates do not
show primitive morphologies as would be expected, but they relate directly
to the diverse modern groups. "Instead of finding a suite of generalized lizards on the stem of the squamate tree, what we found in the Jurassic
were the first representatives of many modern groups, showing advanced morphological features," says Arnau Bolet, lead author of the article.
The observed times of divergence, morphospace plots and evolutionary
rates, all suggest that the Jurassic was a time of innovation in squamate evolution, during which the bases of the success of the group were
established. According to these results, the apparent sudden increase
in diversity observed in the Cretaceous could be related to an improved
fossil record, capable of recording a larger number of species, or to
a burst of origins of new species related to the new kinds of forests
and insects.
Establishing the timing and mode of radiation of squamates is key for not
only understanding the dynamics of terrestrial ecosystems in the Mesozoic,
but also for deciphering how the group achieved an astonishing diversity
of more than 10,000 species, only rivalled by birds among tetrapods.
========================================================================== Story Source: Materials provided by University_of_Bristol. Note: Content
may be edited for style and length.
========================================================================== Related Multimedia:
* The_fossil_of_Jurassic_lizard_Eichstaettisaurus ========================================================================== Journal Reference:
1. Arnau Bolet, Thomas L Stubbs, Jorge A Herrera-Flores, Michael
J Benton.
The Jurassic rise of squamates as supported by lepidosaur disparity
and evolutionary rates. eLife, 2022; 11 DOI: 10.7554/eLife.66511 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/05/220503091754.htm
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