The Earth Story

Snake Fossilized in Amber

The image at the left is a remarkable find from Cretaceous-aged amber in Myanmar; a tiny, few centimeter wide, newborn (or possibly embryonic) snake fossil. This photo was just published in an article introducing this 100 million year old fossil to the world; the picture on the right is an X-ray image that shows the bone structure of this fossil.

The head of the snake is missing, but many interesting things have been learned from this fossil. Along with this snake, they found a segment of skin from another snake, allowing characterization of the species. At the time, Myanmar was a series of islands that had not yet accreted to Eurasia, and the amber itself was formed in trees that lived close to a shoreline, so this sample shows that this snake species lived and bred near shorelines. The morphology is also similar to other snakes from around Gondwanaland at this time, showing that snakes had become widespread by this time, even able to cross bodies of water.

-JBB

Image credit and original paper: http://advances.sciencemag.org/content/4/7/eaat5042

Press report: https://bit.ly/2muUC9X

Auca Mahuevo.

Auco Mahuevo, from the Spanish menaing “more eggs”, a site in Patagonia, Argentina is a Cretaceous lagerstätte discovered by Luis Chiappe, Lowell Dingus, and Rodolfo Coria during two expeditions in 1997 and 1999. The site is famous for revealing an almost perfectly preserved dinosaur nesting site, including embryos, eggs and soft tissue preservation.

Geological Setting and age. The rocks of Auca Mahuevo comprise of sandstones, siltstones and mudstones deposited in a fluvial system. The nesting site occurs in a reddish-brown siltstone, which is believed to represent an over bank flooding deposit from the fluvial system. There appears to be several "layers" of nests, perhaps showing that the Sauropods nesting here did so year after year. Analysis of the palaeotopographic surfaces shows that the some of the nests sit in small depressions about 30cm deep. The site has been dated at 70ma- Late Cretaceous.

Important Discoveries.

The Auca Mahuevo fossil site yielded several important fossils, but the most special are the unhatched dinosaur embryos, found undisturbed in their nests, and these are the first dinosaur embryos found in the Southern Hemisphere. The tiny embryos show fossilised skin, which is similar to that of a modern lizard. One of the fossils shows a stripe of large scales near the centre, and this would almost certainly have been a stripe running down the animals back. Tiny teeth found within the eggs show what type of Sauropods were nesting here, the Titanosaurs. Remains of titanosaurs have been found close by to the sire, and they were also the only sauropod type dinosaurs alive at the end of the Cretaceous period. Other fossilsied skin samples from the Titanosaurs shows that this group of dinosaurs had armoured plates embedded in their skin. The embryo fossils do not show this, indicating that these plates grew after the dinosaurs had hatched.

Preservation

The siltstones covering the Auca Mahuevo nesting site have allowed palaeontologists to ascertain that a flood swept through the area, submerging the nests and preserving them for millions of years. It was this rapid preservation that allowed the soft tissue preservation at the site.

Further Reading; http://www.sciencedaily.com/releases/1998/11/981118081844.htm http://www.lowellcarhart.net/ebay/papers/sauro.pdf http://curiosity.discovery.com/question/what-is-auca-mahuevo (Short Video) http://www.h2g2.com/approved_entry/A684425

-LL

Real Life Jurassic Park?

Many of us have seen the Spielberg’s Jurassic Park and wondered if it was possible to bring the ancient creatures back to life just as the scientists did in the film. Not to worry, these Jurassic beings will not be roaming the streets anytime soon. However, a team of scientists led by Robert Reisz (University of Toronto Mississauga) have made a huge discovery – Jurassic dinosaur embryos.

Previously all dinosaur embryos have been dated to the Cretaceous period, making the samples unearthed by Reisz’s team 125 million years older than the oldest known samples! The team, comprised of scientists from Canada, Taiwan, China, Australia, and Germany, analyzed over 200 embryonic bones samples from different stages of the dinosaur’s development. This is the first time scientists are able to trace embryo growth through different developmental stages.

The samples represented approximately twenty different long-necked dinosaurs known as sauropodomorph Lufengosaurus – the most common early Jurassic dinosaur. The embryos came from multiple nests and showed various different stages of development. Typically dinosaur embryos are not found in such large quantities and have previously only provided a developmental snapshot compared to the latest findings.

Reisz and his team concentrated on the femur; being the largest bone, it is easily identifiable and shows consistent rapid growth, doubling in length across the samples. This rate of growth shows these dinosaurs experienced a very short incubation period.

The image seen here is a cross section of an embryonic femur. A lambda filter was used to enhance visualization resulting in the purple color. The outer honeycomb is embryonic bone tissue, the large spacing allows for blood vessels and osteoblasts (cells responsible for creating bone). The central medullary cavity is crystalized from the fossilization process.

The samples collected indicated the femurs were being constantly reshaped within the egg; this means the dinosaur’s muscles played a key role in bone development. These results are the first real proof that dinosaurs, like birds, moved while inside the egg.

Taiwanese members of Reisz’s team discovered organic material inside the embryonic bones. The researchers were able to use specifically targeted infrared spectroscopy to conduct chemical analysis on the femur bones. The analysis showed evidence of possible collagen fibers. Collagen is a protein typically found in bones. During the fossilization process bones are turned to rock so collagen fiber remnant is a huge discovery!

Only about one square meter of “dinosaur nesting grounds” has been unearthed so far and is a rare find the in fossil world. This treasure trove of dinosaur embryos also contains bits of eggshell – the oldest known eggshell for any terrestrial vertebrate! These dinosaur eggshells are only about 100 microns thick and are the most well-preserved to-date. With these new discoveries we will be able to have a more in-depth look into the dinosaur development process.

-ALT

Source: http://phys.org/news/2013-04-world-oldest-dinosaur-embryo-bonebed.html

Image Credit: University of Toronto

An early horse, fossilised with its foal

The Messel pit (see http://on.fb.me/1VRgpkr) is a delight to all palaeontologists who study the Eocene era, especially those interested in the evolution of mammals, due to its excellent preservation. The mare died shortly before giving birth, possibly as she was taking a drink when the lake released a dose of poisonous ground hugging carbon dioxide. As with many specimens from this site, many soft tissues including the placenta were preserved as 'bacterial photographs', where the microorganisms aligned with the tissues of the dead animal and were replaced by particles of mud. It is the earliest and best preserved mammalian foetus found to date, and the mare's reproductive system was very similar to that of a modern equid.

Loz

Image credit: Senckenberg Forschungsinstitut, Sven Tränkner; http://bit.ly/1QiRF2U http://nyti.ms/1VMreEf

Original paper, free access: http://bit.ly/1QiRF2U

National Fossil Day: http://nature.nps.gov/geology/nationalfossilday/

Dino nest with embryos

This unique piece came up for auction a few years ago, featuring a circular raptor nest, broken eggs and clearly visible embryos. The space where the parent sat is clearly visible, though they obviously weren't around when the sand dune fell onto the nest in what is now Mongolia, burying it for a long eternity that lasted around 65 million years.

Loz

Image credit: Bonhams/ Xinhua/Reuters Photo

Oviraptor nest Oviraptor (egg raptor) started out its palaeontological career in 1924 as a much maligned creature, when scientists supposed it had been trapped by a collapsing dune (as most Mongolian dinosaurs were) in the act of stealing eggs from another type of saurian's nest. After several decades, new finds revealed that it had in fact been sitting on its own eggs, as testified by the embryos discovered within them beneath the brooding parent. They lived in the late Cretaceous about 75 million years ago and may well have been feathered. Loz Image credit: American Museum of Natural History.