Life is just a theory

sciencesoup:

Prehistoric Colours

We typically think of the fossil record as a black and white view into the prehistoric world, but some fossils show that dinosaurs, fish, early insects and even ancient plants were very colourful creatures indeed. A team led by Yale University paleogeologist Maria McNamara have analysed spectacularly coloured fossils of beetles that lived 15–47 million years ago—and these fossils have preserved not only shape and structure, but also the colours of the beetles’ exoskeletons. Many other fossils use pigment traces to generate colour, which bounces light off a chemical, but the beetles’ colours are far richer because they are generated through a phenomenon called structural colouration, in which light bounces off nanometre-scale surface geometries. By analysing the fossils under an electron microscope, McNamara and her team found that the colours had shifted slightly during the fossilisation process—specifically, they had been redshifted , so a blue beetle would have become slightly greener, and a yellow one would have become slightly oranger. After correcting for this shift, the team can envision the beetles’ flashy metallic exoskeletons just as they looked when they were alive. These colours also give clues about how the beetle lived, allowing the researchers to determined whether they served visual functions like thermo-regulation or communication.

(Image Credit: Wired)

thepredatorblog:

Basilosaurus is a genus of cetacean that lived from 40 to 34 million years ago in the Late Eocene. Its fossilized remains were first discovered in the southern United States (Louisiana) and were initially believed to be some sort of reptile, hence the suffix -“saurus”, but later found to be a marine mammal.

Basilosaurus averaged about 18 meters (60 ft) in length, and is believed to have been the largest animal to have lived in its time. It displayed an unparalleled degree of elongation compared with modern whales. Their very small vestigial hind limbs have also been a matter of interest for paleontologists.

dailyfossil:

Saurosuchus 

Mounted specimen from Ischigualasto Provincial Park, San Juan, Argentina

Reconstructed model from the Titanes de Ischigualasto (Titans of Ischigualasto) exhibit while at the Museo Argentino de Ciencias Naturales in Buenos Aires, Argentina. 

When: Late Triassic (~231 to 226 million years ago)

Where: Argentina

What: Saurosuchus is a very large basal member of the crocodile lineage within the Archosauria. It lived in what is now Argentina during the late Triassic, where it was a dominante apex predator, reaching lengths of up to 23 feet (~7 meters).  A good deal of this length was its massive skull filled with pointy recurving teeth. Saurosuchus is a member of the Rauisuchia, one of the first branches to come off of the Crurotarsi (crocodile line archosaurs) lineage.  Like other rauisuchians Saurosuchus had an erect leg posture, you can see this in the model above, it looks very much like a large crocodile, but its legs are directly underneath its body, not sprawling out like in modern crocodiles. This posture is the same as in mammals and dinosaurs, but was accomplished in a different way. Mammals and dinosaurs modify the femur itself for erect posture, but in rauisuchians it was the pelvis that was transformed. Saurosuchus was a fully terrestrial creature capable of fast speeds as it hunted its prey (including the much smaller dinosaurs) in the ancient flood plane. 

Saurosuchus fossils are from the Ischigualasto formation (and national park!) in Argentina. This area is open to the public and is more popularly called the Valle de la Luna (Valley of the Moon).  Not only do basal crocodile line archosaurs come from this formation, but some of the oldest dinosaurs as well. These animals, which would go on to dominate later in the Mesozoic, were a minor part of the fauna. The Triassic here was dominated by rhynchosaurs and cynodonts, these groups would both suffer great losses during the end Triassic extinction event.