It also suggests that fossil tracks long believed to be the work
of early tetrapods could have been produced instead by lobe - finned ancestors of the lungfish.
The findings are reported by researchers from Tokyo Institute of Technology (Tokyo Tech), the Centre for Genomic Regulation (CRG, Barcelona) and their collaborators in the journal eLife and give new insight into how fish evolved to live on land in the form
of early tetrapods.
The researchers wanted to test what factors could have driven diversity in skeletal design in the evolution
of early tetrapods.
The shoulders and pelvis
of early tetrapods expanded and strengthened, allowing for load - bearing on land.
A 2012 reconstruction
of early tetrapod Ichthyostega suggests that it couldn't bend side - to - side like lizards do as they walk.
«All of them are a little weird,» says Cambridge University professor emeritus Jennifer Clack, the grand dame
of early tetrapod research.
«It's tempting to attribute alternating impressions to something like the footfalls
of an early tetrapod with digits, and yet here we've got good evidence that living lungfish can leave similar sequences of similar gait,» said Coates, PhD, professor of Organismal Biology and Anatomy.
Not exact matches
While some invertebrates had transitioned from marine to terrestrial environments millions
of years
earlier, even more came ashore during this period, along with the
tetrapods.
The same sites have also produced some
of the
earliest post-Devonian
tetrapods, four - limbed creatures that included some
of humanity's
earliest relatives, filling a post-extinction lull in their diversity known as Romer's Gap.
An
early tetrapod is shown at the top
of the image.
Emma Dunne, from the University
of Birmingham's School
of Geography, Earth and Environmental Sciences, said: «This is the most comprehensive survey ever undertaken on
early tetrapod evolution, and uses many newly developed techniques for estimating diversity patterns
of species from fossil records, allowing us greater insights into how
early tetrapods responded to the changes in their environment.»
The team compared the fish's bones and head structure to fossils
of a more primitive fish and an
early tetrapod.
The researchers analyzed a skull
of Panderichthys — an ancient fish that evolved at about the same time as
tetrapods (
early four - legged land - dwellers) from a common ancestor.
A new study comparing the forces acting on fins
of mudskipper fish and on the forelimbs
of tiger salamanders can now be used to analyze
early fossils that spanned the water - to - land transition in
tetrapod evolution, and further understand their capability to move on land.
However, the most
of basal bones located in the anterior side (i.e. the thumb side in the human limb) were lost in
early tetrapods, and only the most posterior bone remained as the «humerus (i.e. the upper arm
of humans).»
The first four - legged, land - living creatures — known as
early tetrapods — evolved from fish, following the transformation
of fins into limbs.
The footprints are 18 million years older than the
earliest known examples
of fossilised
tetrapod bones.
«The pattern
of co-occurring species remained stable through the evolution
of land organisms from the
earliest tetrapods through dinosaurs, flowering plants and mammals,» said Anna K. Behrensmeyer, a paleobiologist with the Smithsonian's Museum
of Natural History and a co-author
of the study.
This family
of loaches, sometimes called sting - loaches, is found in Eurasia and Morocco and has about 28 genera with about 236 species (Berra The evolution
of tetrapods began about 400 million years ago in the Devonian Period with the
earliest tetrapods evolved from lobe - finned fishes.
The evolution
of tetrapods began about 400 million years ago in the Devonian Period with the
earliest tetrapods evolved from lobe - finned fishes.