#naturalsciences
Pterosaurs, flying reptiles and close relatives of the dinosaurs, already developed feathers of different shapes and colours. This has been proven by a 115 million year old Brazilian fossil, studied by a team of palaeontologists. ‘Coloured feathers were used to show off’, says palaeontologist Aude Cincotta of the Royal Belgian Institute of Natural Sciences (@rbins). ‘Our study suggests that coloured feathers could already have appeared in the common ancestor of dinosaurs and pterosaurs.’
An international team of palaeontologists and geologists has found new evidence that pterosaurs had feathers of various colours. The discovery provides more insight into the origin and function of primitive feathers. The researchers published their findings in Nature.
The team from Brazil, Ireland, Belgium and France studied a 115 million-year-old pterosaur fossil from the Crato Formation in north-eastern Brazil. The fossil of this Tupandactylus imperator consists of the skull topped by an enormous crest of soft tissue, that has not been fossilized, but of which the imprint has been preserved. Feathers were attached to the base of the crest.
‘This is a spectacular discovery,’ says researcher Aude Cincotta (RBINS), who led the study. ‘For a long time, there was discussion about whether pterosaurs had feathers. As of now, we have firm evidence that this was indeed the case, and that the feathers were quite complex. We were able to distinguish two types of feathers in this Brazilian fossil: elongated, unbranched feathers and small branched feathers. The discovery of branched feathers is new in pterosaurs. They were only known for certain carnivorous dinosaurs, the theropods, ancestors of birds.’
Showing off
A second important finding: fossil melanosomes. These are microscopic structures in the skin and in certain organs that contain the pigment melanin. In today’s birds, the shape of these melanosomes determines the color of the feathers. The analysis shows that the melanosomes in the two types of pterosaur feathers as well as in the soft-tissue crest have a different shape (elongated, ovoid or spheroid). These differences were only known in theropod dinosaurs (including birds).
This study shows that pterosaurs already had feathers with colour variations and that they were probably used for visual communication and display: to show off. The fact that these pigmented feathers are found in both dinosaurs and pterosaurs suggests that their common ancestor in the Middle or Late Triassic (about 250 to 200 million years ago) already had the ability to sport colored feathers.
Safeguarding fossils
Thanks to cooperation between Belgian and Brazilian scientists, national authorities, and a private collector, the pterosaur fossil could be repatriated to Brazil in February 2022. ‘It is so important that scientifically important fossils such as this one are returned to their countries of origin and safely conserved for posterity,’ says Edio-Ernst Kischlat of the Brazilian Geological Service, who co-authored the study. ‘These fossils can then be made available to scientists for further study and can inspire future generations of scientists through public exhibitions that celebrate our natural heritage.’
[Video: Stéphane Van Israël, @rbins]
Trix vs Stan! Come and admire the two T. rexes currently exhibited @rbins.
In the first two pictures is the 3D-printed version of Trix, the specimen of our Dutch friends of Naturalis in Leiden. In the last two pics you see our cast of Stan.
Both of them:
- were top predators during the very last part of the Upper Cretaceous period, the last chapter in the book of dinosaurs (avian dinosaurs as current birds have written a nice sequel! )
- were excavated in the Hell Creek Formation of North America: Trix near Jordan in Montana , Stan near Buffalo in South Dakota (a 4 hour drive from each other).
- were prepared by the Black Hills Institute in Hill City, South Dakota
- are among the most complete of some thirty T. rex specimens known today
- have healed bite marks and wounds probably caused by other T. rexes
- had 50 to 60 teeth, some as big as bananas . They are robust and serrated allowing T. rex to bite through flesh and bone. The teeth were replaced throughout their lives.
- had well-developed senses: olfactory lobes almost as large as their brain, a highly developed inner ear that could perceive low frequency sounds, and small eyes ️ located towards the front of the skull (like we have) which demonstrates stereoscopic, 3D vision.
They also differ:
- Trix is seen as a female, Stan as a male, although palaeontologists are still debating…
- Trix is a bit longer and higher than Stan : 12.5 m vs 11.7 m; 4 m vs 3.64 m
- Both were old when they died, but Trix is the oldest T. rex so far: more than 30 years of age
- Trix is estimated to be at least 67 million years old, Stan 66 million.
- Stan was named after its finder: amateur palaeontologist Stan Sacrison, who discovered the first of Stan’s bone fragments. Trix is both an allusion to “T-rex” and to former Queen Beatrix of the Netherlands: so Trix is the Queen of the Cretaceous!
- Stan has had more admirers so far as he is all over the world: it’s the most duplicated T. rex fossil.
- Trix is publicly available for research, Stan for the moment is not. The original specimen was auctioned and sold for 31.8 million dollars to an anonymous private buyer in 2020, making it the most expensive fossil ever sold. Its future as a study object and museum exhibit is uncertain at this moment.
[Pictures of Trix on Instagram by visitors @pavel_sb and @mrdieds ; of Stan by @elisebormans and @ omar_cirilli]
Belgian mussels developed stronger shells
Belgian mussels have developed stronger shells over the last hundred years. More calcareous shells protect them better from crabs’ claws and seagulls’ beaks. These predators have increased significantly in number during the last fifty years. ‘Belgian mussels adapt surprisingly well to new environmental conditions’, says biologist Thierry Backeljau (RBINS). ‘They might be more resilient to climate change than we think.’
An international team of biologists analyzed the calcareous structure of mussel shells that were collected along the Belgian coast this last century. You would expect the shells to become thinner because more acidic seawater - due to the increase in CO2 in the atmosphere - breaks down calcareous matter. But the team observed a marked increase in the calcification of mussel shells.
The main causes of the more calcareous mussel shells are changes in predators. The dog whelk (Nucella Lapillus) disappeared at the end of the seventies, after which the number of crabs and seagulls increased during the 1980s and 1990s respectively. This led to a pressure on mussels to develop thicker shells, protecting better against the crabs’ claws and the seagulls’ pecking beaks. According to the scientists, this might mean that our Belgian mussel populations can better cope with future climate changes than previously thought.
A special collection
The researchers evaluated a total of 268 mussels that were collected between 1904 and 2016 on the breakwaters between Nieuwpoort and Ostend. The specimens collected between 1904 and 1987 are part of the collections of the Royal Belgian Institute of Natural sciences (RBINS). This unique collection of one single species is composed of ‘wet’ specimens (shells and body tissue, preserved in ethanol), and ‘dry’ specimens (shells only). They were collected during monitoring programs over the past century. ‘This mussel collection is unique,’ says biologist Thierry Backeljau (RBINS), co-author of the study. ‘It may sound paradoxical, but to have such an extended collection of an animal that is so ubiquitous is rare. Researchers usually focus on exceptional species.’
Dog Whelks and acidification
The dog whelk is an important predator of mussels in the North Sea. Dog whelks make a small hole in the mussel shell, through which they suck the mussel empty. To do this, they must drill through the dark, organic outer layer of the mussel: the periostracum. Mussels with a thicker periostracum are better protected against this type of predator. This created a selective pressure on mussels, favoring a thicker periostracum. The acidification of the North Sea - which breaks down calcareous matter - led to additional pressure in favor of more periostracum, offering better protection to the underlying calcareous layer.
But as of the late 1970s, things changed. The dog whelk population suddenly declined sharply and even died out locally due to the use of tin based paint on ship hulls, particularly tributyltin hydride (TBT). The selection pressure on mussel populations in favor of more periostracum decreased.
Crabs and seagulls
In the meantime, average spring and summer temperatures of North Sea surface waters continued to rise, in line with global ocean trends. The input of minerals and nutrients from the land also increased steadily over the past sixty years due to the discharge of fertilizers and wastewater into rivers (eutrophication). The result: an increase in the amount of algae and thus a greater food supply for all kinds of organisms, including the larvae of decapods such as crabs and lobsters. As a result - helped by overfishing of cod, which feeds on those larvae - the number of crabs and lobsters skyrocketed from the 1980s.
Just like the dog whelk, crabs and lobsters are fond of mussels, which they crush with their claws. Protection by a periostracum makes little difference against this, but a stronger, more calcareous shell does. Moreover, depositing calcium requires less energy than producing a periostracum. Thus, a new selection pressure arose, in favor of more calcareous shells.
This selective pressure was reinforced by the exponential population growth of seagulls in the 1990s, due to the increased number of decapods. The breeding season of seagulls (May and June) coincides with the peak of decapods, which are an important food source for the chicks. But seagulls also eat mussels and increased the selection pressure in favor of a calcareous, solid shell.
Hope for the future?
This study shows that the global effects of climate change, such as ocean acidification, do not simply apply on a local scale. Complex, local changes in ecological conditions can lead to biological outcomes that appear to conflict with predictions on a global scale.
‘The Belgian mussel populations seem able to adapt their shell formation to a wide range of local selection pressures and perturbations’, says Backeljau. ‘This gives hope for the future: mussels may be better armed against climate change than we thought.’ This research also illustrates the importance of natural science collections, such as those of the RBINS, in the study of, and fight against, climate change. ‘Collections and archival specimens help us investigate long-term effects of changes in the environment, which is difficult with experimental studies. It is a powerful research method that, as shown here, can yield surprising results and help us get a clearer picture of historical ecological changes’, concludes Backeljau.
The study was published in Global Change Biology.
Post link
We love the composition of this by visitor @mrdieds. This is our Gallery of Evolution.
You will travel through 541 million years of evolution of life on this planet, stopping off at six key moments: the Cambrian explosion, the proliferation of aquatic life during the Devonian era, the conquest of land during the Carboniferous period, the swarming seas of the Jurassic era, the appearance of mammals in the Eocene period, and - as you see here - the impact of humans in the present day.
Evolution is of course not limited to the past: species continue to change. Today, human beings are having an undeniable impact on life on our planet. Artificial selection, genetic modifications, overfishing, selective hunting, the destruction of ecosystems, and the introduction of exotic species are all human factors that are causing important changes and even the extinction of many species.
Want a quick 360° drone flight through life’s evolution?
[picture:@mrdieds]
Picture of our facade by a chimney sweep (!), who was working across the street!
Do you know what is hiding behind our brown facade? The whole world! Shielded from sunlight and heat, you will find a great part our natural sciences collections there. One of the largest in Europe: 38 million specimens, from the four corners of the world. Each and every one of them bears witness to what lives, may soon no longer live, and what once has lived.
So imagine storage rooms with rows of oak cupboards crammed with carefully described insects, rooms with shelves full of invertebrates preserved in alcohol, drawers with vertebrates, and anthropological collections including Neanderthals found in Belgium… And of course we also have fossil collections - from trilobites to dinosaurs - and geological collections, with minerals and meteorites.
These collections are the result of many decades of exploration and research, and help us better understand the history of life on Earth, and to come up with better ways of protecting the biodiversity and geological diversity today. With modern technology (DNA analysis, imaging techniques, …) scientists are making new discoveries about this natural heritage.
Check out (a small part) of our collections in high res on virtualcollections.naturalsciences.be
[picture: @rooftopvermandel, Instragram]
