Monday, 24 July 2017

Frogs may have evolved the first kneecaps on Earth

7 July 2017

By Andy Coghlan

Frogs legs have sprung a big surprise – contrary to textbook biology, they have primitive kneecaps.

The kneecaps are made of dense, fibrous cartilage rather than bone, and appear to be much better suited to soaking up the strains of leaping and jumping than the bony human patella.
They may have been missed until now because they are not clearly visible on frog leg bones, even with a microscope, says Virginia Abdala of Argentina’s Institute of Neotropical Biodiversity, who led the investigation. The researchers analysed full skeletons of 20 species, but they were only able to see kneecaps in the eight specimens from which they took tissue slices for analysis.

One implication of the discovery is that kneecaps like this began to evolve in the Devonian period 400 million years ago, when the first four-legged animals reached land, the researchers say.

“Until now it was thought that the evolution of kneecaps coincided with the arrival of tetrapods that lay eggs on land or retain fertilised eggs in the body,” says Abdala. This investigation shows that the process really started with fibrocartilage in frogs, she says.

Spiders lure bees for dinner by making flowers look flashier

10 July 2017

By Katie Langin

Ambush hunters normally rely on the element of surprise, opting to stay hidden until the moment of attack. But some spiders go for a flashier strategy. They reflect UV light, which makes the flowers they sit on appealing to bees – a bizarre strategy that has evolved multiple times in crab spiders, which ambush their prey instead of catching it in webs.

Felipe Gawryszewski at the Federal University of Goiás in Brazil and his team collected individuals from 68 species of crab spider in Australia, Europe and Malaysia. All of the species hunted insects using a sit, wait and pounce strategy, but some did so on drab substrates like bark and leaves while others hunted on flowers.

Using genetic information from all these species, the team pieced together a “family tree”, which showed that the flower-based hunting strategy evolved multiple times. What’s more, flower-dwelling crab spiders reflected more UV light than non-flower dwellers.
This appears to be an effective hunting strategy as bees are more likely to visit flowers when UV-reflecting spiders are perched atop them.

Ancient species of ‘supercroc’ had serrated, T. Rex-like teeth

July 6, 2017

by Chuck Bednar

A giant crocodile-like creature that lived in Madagascar more than 150 million years ago had a large jaw and serrated teeth similar to those of the Tyrannosaurus rex, suggesting that it, like the predatory dinosaur, fed on bones and other hard animal tissues, a new study has revealed.

The species, whose scientific name is Razanandrongobe sakalavae (“giant lizard ancestor from Sakalava region”), had straight legs and a skull unlike those of modern-day crocodiles, according to BBC News. It is thought to be the earliest and largest member of a group of early crocodilians known as Notosuchians – a clade which lived during the Jurassic and Cretaceous periods.

In fact, in a press release, lead author Cristiano Dal Sasso from the Natural History Museum of Milan and his colleagues reported that Razanandrongobe sakalavae (Razana, for short) predates what had been the earliest-known Notosuchians by around 42 million years.

Based on the shape of the skull and an analysis of the creature’s anatomical features, Dal Sasso and his colleagues identified Razana as a relative of South American baurusuchids and sebecids, a group of predators that had deep skulls and powerful erect limbs. Razana was reportedly about 7 meters long and weighed between 800 and 1,000 kilograms (about 1,700 to 2,200 pounds).

A twist in the tail: Flying fish give clues to 'tandem wing' airplane design

Date:  July 5, 2017
Source:  Society for Experimental Biology

Summary:  Ribbon halfbeak are a species of fish with the ability to fly above the sea surface -- but unlike true 'flying fish', they lack the necessary hind wing fins. So how do they fly?

Elephant seals recognize each other by the rhythm of their calls

Date: July 20, 2017
Source: Cell Press

Summary: Every day, humans pick up on idiosyncrasies such as slow drawls, high-pitched squeaks, or hints of accents to put names to voices from afar. This ability may not be as unique as once thought, researchers report. They find that unlike all other non-human mammals, northern elephant seal males consider the spacing and timing of vocal pulses in addition to vocal tones when identifying the calls of their rivals.

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