If you hadn’t heard recently a story broke on numerous websites that some researchers had found ” building blocks of life” in a meteorite. Numerous headlines stated that we were aliens and other such things to grab the attention of readers. I’ve never found science journalism to be particularly great at explaining things so I thought I might clarify things a little. Several researchers from around the world ( Imperial College London, Nasa Goddard Space Flight Centre, Radboud University Nijmegen etc.) extracted and analyzed a 15 g sample from the interior of the Murchison meteorite.

They crushed it and going through an extensive purification process eluted out any organic compounds they could find. Then using mass spectroscopy ( a way of determining what a compound is by ionizing it and firing it against a detector and determining it’s time of flight) they determined samples of both uracil and xanthine were present in the meteorite. This actually fairly cool since uracil is a component of RNA and xanthine is an intermediate in the biosynthetic pathway to guanine, another nucleobase found in both DNA and RNA.

It was determined through isotope analysis of these samples that significant proportions of the carbon atoms found in them were of carbon 13 indicating that the molecules likely formed extraterrestrially since carbon 13 is rarely found on earth.

A damn cool story but it’s not like they’ve found incontrovertible evidence that earth was seeded from the heavens by aliens. It just means that life on this planet may have been partially jump started by these biological precursors from the stars, which is still fairly cool I think.

Incidentally, xanthine is one of the intermediates in the pathway that leads to caffeine. Looks like it’s always had a role in getting things going

Reference:

Martins, Z. et al. 2008. Extraterrestrial nucleobases in the Murchison meteorite. Earth and Planetary Science Letters 270: 130-136

Dinos likely didn’t really have feathers…

The theory that dinosaurs gave rise to birds has been dealt a blow by palaeontologists who have examined critical evidence from a Chinese fossil.

The discoverers of the turkey-sized dinosaur Sinosauropteryx say it would have had primitive feathers, supporting the bird-from-dinosaurs theory.

But the latest research says these ‘proto-feathers’ are really frilly structures on the creature’s back.

The meat-eating dinosaur was covered in these fibers that looked like they could have been primitive feathers. These feathers were not said to be used of flight but were there only for aesthetic purposes.

Under a high powered microscope it turns out the feathers were actually the remains of a frill of a collagen fiber that would have ran down the dinos back. THis is the same sort of fiber that is found on the back of common day reptiles.

However this small set back doesn’t discredit the amount of other discoveries that could link dinosaurs to birds. The archaeopteryx (seen in the picture at the top of this post) is known as the very first bird, and most definitely evolved from dinosaurs… it fills in a huge gap in the fossil record, but still leaves a lot of space for debate.

The theory that dinosaurs evolved into birds mostly stands on the shoulders of the idea that smaller dinosaurs gained their evolutionary advantage by growing feathers to keep warm and to fly to high levels for safety. 

The animal with the earliest sexual differentiation.

Name: diictodon (DY-ik-toe-don) means two teeth
animal: therapsid reptile
size: 45 cm long
diet: herbivore
lived: 256 - 252 mya
found: Africa and Asia
fossil:

In the late Permian period, the same time as the gorgonopes, these extremely common mammal-like synapsids burrowed deep in the ground living in couples, probably staying with the same partner its entire life. It’s head was large, with a beak that had no teeth except two saber like tusks. The tusks are extremely important as they are the characteristic of the first sexual dimorphism in all of animal history. Only the males were found having the pair of tusks. It lived in deep narrow tunnels protecting it from harsh weather and larger predators - making it an extremely successful animal of its time.

The diictodon were abundant, not only would you find multiple burrows within the same patch of land, their fossils also make up about 1/2 of all backboned animals in South Africa from the Late Permian Period. None of the burrows were interconnected further stressing the theory that the diictodon were strictly monogamous. A small chamber at the end of the burrow would have vegetation for comfort, this is where the diictodon female would have and raise her children.

These underground burrows would have been excellent for times of drought. The burrows would have remained cooler, and had a damp environment. The diictodon could also feed on the roots that were underground. The animals would, however, build their burrows in areas that were not so great, such as river banks. They burrows would often flood killing the animals. The particular fossil above is a pair of diictodon that were cuddled together when flood struck.

The diictodon’s arms and legs did not lack in strength, still they were strictly herbivores. It had an excellent sense of balance, sight and smell. It would use these keen senses to dart in and out of its burrow knowing danger was not near. It would then use its beak to break of vegetation and other plant pieces to eat and use in their housing.

The diictodon is widely studied since it is such an abundant animal. Not only was it the first animal with sexual differentiation, it was also the missing link between reptiles becoming mammals. This little reptile is thus a hugely important link in the evolutionary chain.

The finding of the sexual dimorphism led scientists to believe there was an extremely complex set of social behaviors within the diictodon community. They could have been used to combat other males in an attempt to find a mate, or could have been used ritualistically.  These tusks gave rise to unbelievably huge developments in mammals in the near future.

With a name like “Gorgonops” I expected it to look more sci-fi-ish.

Name: Gorgonops (gore-gon-ops) “Gorgon’s arch”
Animal type: Therapsid reptile
lived: 252 - 248 mya
diet: Carnivore
size: 3.5 meters
found: Africa
fossil:

The Earth was slowly dying as it Pangaea died up from coast to coast, temperatures were getting higher and higher very quickly and rainfall became more and more scarce. In these harsh conditions few animals were surviving. The gorgonops was preying on anything that was left. It was a gigantic carnivorous reptile, the size of an elephant but moving sleek and quickly like a fox. It had large, long and sharp teeth permitting it to take down large animals with its strong jaw. It also had two long saber teeth, one of the first animals to have such a thing.

The gorgonops was extremely well adapted for life in these harsh conditions. Its long and upright legs allowed it to walk and run efficiently while it’s keen eye sight and sense of smell made it a very dangerous predator. The animals probably lived in groups, hunting during the cooler times of day and resting in the shade at peak hours. It would have taken several of the animals to take down the larger herbivores dwelling in the same areas.

The gorgonops is a member of the therapisid family - a group of reptiles that adapted well to change, were cold blooded and had a variety of mammalian characteristics. Their long legs tucked under the body and their oddly shaped teeth (odd for reptiles) gave way for the first mammals to evolve such as the thrinaxodon. Although the gorgonops seemed to be a wonder animal fully adapted for harsh weather it did not survive the great extinction 248 mya, mostly due to the fact that most of the animals they hunted became extinct.

First known herbivore reptile to evolve.

Name: Edaphosaurus (ed-eff-oh-saw-rus) “pavement lizard”
animal type: synapsid (pelycosaur) repitle
lived: 282-256 mya
size: 3 meters long
found: North America and Europe
fossil:

This animal looked a heck of a lot like the dimetrodon that I covered a while ago, but the two animals are distantly related and extremely different. The most obvious difference being that one was a ferocious meat eating predator while the edaphosaurus stuck to plants. Until this time all reptiles and amphibians had been carnivorous or insectivorous. Plants don’t hold nearly as much energy and proteins as the meats did - so animals would have to eat a lot more of them than they would meats to extract enough energy to life on.

Animals like the edaphosaurus  evolved different features in order to be able to properly tackle the plant life on earth. Their peg-like teeth could tear leaves apart like there was no tomorrow, and could break down twigs and branches with their powerful jaw. Even more teeth were found in the roof of the edaphosaurus’ mouth to further mash up the plant before it reached the stomach.

It’s large body allowed for a lot of food to be taken in at one time. It’s long gut would extract all the nutrients possible from its poor and limited diet of surrounding plants. The edaphosaurus would have liked swampy areas but could have survived in harsher desert climates. Its large sail, like on the dimetrodon, was used to regulate its temperature.

Just three more before dinosaur time!