Triassic fossils that reveal origins of living amphibians
Palaeontologists from the US have discovered the oldest-known caecilian fossils ever – extending the history of caecilians 35 million years back to Triassic Period, roughly 250 million to 200 million years ago.
Modern caecilians are limbless amphibians which look like large worms or snakes, with cylindrical bodies and a compact, bullet-shaped skull that helps them burrow underground. Today, they make their home burrowing in leaf-litter or soil in South and Central America, Africa, and Southern Asia.
The fossil was discovered in 2019 during a dig at Arizona’s Petrified Forest National Park in the US.
Prior to this only 10 fossil caecilians, dating back to the Early Jurassic Period about 183 million years ago, had ever been found.
But with DNA studies estimating the evolutionary origins of this group to some 370 million to 270 million years ago, there had been an 87-million-year gap unaccounted for in the fossil record.
“Seeing the first jaw under the microscope, with its distinctive double row of teeth, sent chills down my back,” says Ben Kligman, a PhD candidate in the Department of Geosciences at Virginia Tech College of Science in the US.
Kligman co-discovered the fossil alongside Xavier Jenkins, now a Ph.D. student at Idaho State University.
“We immediately knew it was a caecilian, the oldest caecilian fossil ever found, and a once-in-a-lifetime discovery,” he says.
The fossil has been named Funcusvermis gilmorei – inspired by the Ohio Players’ 1972 song Funky Worm, while honouring Kligman’s mentor Ned Gilmore, the collections manager at the Academy of Natural Sciences of Philadelphia’s Drexel University.
The research has been published in the journal Nature.
People can tell a giraffe is a giraffe just from the way it moves
A new study has used neuroimaging to compare how the brain processes objects in static images and dynamic videos, finding that the brain uses motion cues to decipher how we see objects.
“There is a lot of information about an object just in the way that it moves,” says Dr Maryam Vaziri-Pashkam, cognitive neuroscientist a research fellow at the National Institute of Mental Health in the US.
“In this study, we wanted to see how good people were at deciphering objects by movement and what brain regions are used to extract this information.”
The team developed short animations that capture the outline of a moving object depicted only with dots – no shape, colour, or other visual cues – that move among a cascade of like-sized dots. The categories included human, to mammal, reptile, tool, ball, and pendulum objects.
The research team asked 430 participants to identify the object in each video, finding that participants could accurately identify the objects 76% of the time.
A smaller subset of 15 participants then viewed the video material, and the corresponding still images of the same object, while receiving a functional magnetic resonance imaging (fMRI) scan. The data revealed that the brain regions that process static and animated images overlap, and identified new regions not previously associated with object categorisation.
“It is not just about form or motion,” explains first author Sophia Robert, a PhD candidate in the Department of Psychology at Carnegie Mellon University in the US.
“The brain is built to grab as much information as it can from the environment to optimise speed and accuracy when categorising an object.”
The research has been published in the journal Neuroscience.
The Powerful Owl is made more vulnerable by rat poison
In the Dandenong Ranges east of Melbourne in Australia scientists are dedicated to the plight of a tiny, but powerful, owl family.
The Powerful Owls are Australia’s largest owl, but they’re listed as vulnerable in Victoria; their populations have diminished and become fragmented due to the significant amount of land clearing since European settlement.
Many are also succumbing to the effects of rodenticide poisoning – a class of anticoagulant poisons used to kill rats and mice by preventing blood clotting, resulting in internal or external bleeding and death.
Second generation rodenticides only require a single dose to poison a rat or mouse and are slow to break down in their system. This means that they’re more likely to lead to secondary poisoning when an owl eats the rodent.
A study on the impacts of rodenticide poisoning on Powerful Owls has even found anticoagulant rodenticides in 83% of owls.
The Powerful Owl Research Team at Deakin University are doing further research into the risks of their use, but Associate Professor John White says that “reducing the amount or even banning the use of rat poisons by the public and limiting it to professionals may well have a positive impact for quite a bit of wildlife.”
Bio printed artificial skins can be used in cosmetic and drug testing
Bioengineered artificial skin is becoming increasingly important in the drugs and cosmetic industries as a substitute for testing on animals.
These artificial skin models are already being produced manually, but 3D bioprinting presents a promising method for producing them on a large scale – if it can be validated in comparison to the traditional approach.
“Calling the model ‘artificial skin’ makes it sound synthetic, but actually it’s human tissue that closely resembles natural skin and is very suitable for safety and efficacy testing of bioactive compounds,” says Silvya Stuchi Maria-Engler, a professor and researcher at the São Paulo Research Foundation’s (FCF-USP) Department of Clinical and Toxicological Analysis, in Brazil.
Maria-Engler is senior author of a new study in the journal Bioprinting in which her team tested the quality and performance of manually-pipetted and extrusion bio printed artificial skins and found they performed equally well.
One of the validation tests included applying reference chemicals classified as irritants (such as acids) and non-irritants, to distinguish between their effects as a way of assessing the potential of materials.
“These findings prove that our bio printed skin can be used instead of the Draize test, an acute toxicity test that applies the substance directly to rabbit skin. Besides the avoidance of animal testing, it’s less subject to human error and variability in the responses obtained by the cosmetics industry,” explains Julia de Toledo Bagatin, first author of the article and a PhD candidate at FCF-USP.