Ability to Regenerate Limbs/Digits Dates Back at Least 300 Million Years
by Ian Randall
Researchers have found the earliest evidence for limb regeneration in the fossil record. Rocks unearthed in southwestern Germany have captured 300-million-year-old amphibians that have one or more regrown limbs.
Unlike humans—who can only replace lost fingertips—salamanders are the only modern four-legged animals, or tetrapods, that maintain the ability to regenerate entire limbs throughout their lives. If tissue has been severely damaged or if the wound heals poorly, however, the regrown limb may grow back incorrectly. Such deformities can be quite common, especially if the same limb is repeatedly amputated or injured, leading to regenerated limbs with extra, missing, or fused-together digits in distinctive and unique patterns.
In their new paper, published online today in the Proceedings of the Royal Society B, the researchers report identifying these same types of deformity in exceptionally well preserved fossils of the early amphibian, Micromelerpeton (pictured, with an extra, partly fused digit, second from the top)…
(read more: Science News/AAAS)
images: Ghedoghedo and Kai Nungesser
Ziapelta sanjuanensis is a new ankylosaurid from the Kirkland Formation of New Mexico. The holotype consists of a complete skull, two partial cervical half rings (neck armour plates), and miscellaneous osteoderms. It was contemporary with the Kaiparowits formation, however Ziapelta shows little resemblance to what ankylosaur remains have been found there. What’s really interesting about this ankylosaur is where phylogenetic analysis has recovered it - Ziapelta is much closer to other North American ankylosaurs such as Euoplocephalus and Scolosaurus than its contemporary, Nodocephalosaurus. Astonishingly, Nodocephalosaurus recovers within a clade of Asian ankylosaurs including Tarchia and Pinacosaurus. What this exactly implies for the radiation of derived ankylosaurids is currently not clear.
The PalaeoFellows only just heard about this and did not feel like drawing an ankylosaur (well no, I admit, it’s just me), so we didn’t produce a reconstruction for Ziapelta. Reconstruction up top by Sidney Mohr.
Another new dinosaur!
So, got some pre production photos of the plushies through. Look at that; embroidered details and applique patch on the back!
Initially he had a bad case of duck-face which was righted, as you can see in the lowest photo. He’s all approved and ready for production now!
By far the most abundant animal found in the Burgess Shale, Marrella splendens has become emblematic of this internationally renowned fossil formation. Described by Charles Walcott as a “lace crab,” Marrella was for years considered to be some sort of aberrant trilobite. After Harry Whittington’s examination of the animal, it was found instead to be a stem-arthropod — falling outside all other known arthropod groups. However, as with many Burgess Shale organisms, its exact position in the arthropod family tree is still uncertain.
Marrella serves as a perfect example of how incredibly common fossil animals can still be exceptionally strange, and how large sample sizes don’t always result in easy answers.
Top image: Fossil of Marrella splendens. (source)
Bottom image: Reconstruction of Marrella, provided by the wonderful Matt Celeskey.
Handmade “Neon Limelight” pterodactyl plush
stuff for my uni book on H. antecessor!! i have about 20 more pages to go ahah