>one researcher estimates as many as a third of dinosaur species might actually be juveniles of other species

I find the idea fascinating. Can't wait for more data.

cross-posted from: https://lemmy.ml/post/13725497

> Title photo- life reconstruction of Aysheaia pedunculata > > Travel back in time to the Cambrian Era, a period famous for the diversity of its life forms! > > Lasting approximately 53.4 million years from the end of the preceding Ediacaran period 538.8 million years ago (mya) to the beginning of the Ordovician period 485.4 mya. It is a period where the atmosphere had elevated concentrations of oxygen, and the global temperature increased-creating a temperate world > > ! > > Geological timescale from here > > Scientists believe that the higher oxygen levels, and warmer climate contributed to the incredible diversity of life that occurred in the oceans. > > However, on land it was mostly barren...complex lifeforms were non-existant and would have been restricted to mollusks and athropods emerging from the water to feed on micobes in slimy biofilms > > The Cambrian is unique as it had unusually high deposits of lagerstätte sedimentary deposits, these sites offer exceptional preservation of 'soft' organism parts, as well as their harder shells which means that the study and understanding of the fossilized life forms surpasses some of later periods > > Which brings us to Aysheaia! > > >It is an extinct genus of soft-bodied lobopodian, known from the Middle Cambrian Burgess Shale of British Columbia, Canada source > > Described as looking like a 'bloated caterpillar' with spines. It was a segmented worm like animal 1 to 6 cm in length and about 5 mm wide > > Comprised of 10 body segments with each segment having a pair of spiked annulate legs (consisting of rings or ringlike segments). It did not have a separate head, its mouth occupied the front of the body along with 6 finger like projections, and 2 grasping limbs on it's 'head'. > > ! > > Diagrammatic reconstruction of Aysheaia pedunculata > > > ! > > Reconstruction of A. pedunculata > > It was similar to modern terrestrial Onychophora (velvet worms). However, it differs due to a lack of jaws and antennae, and possible lack of visual organs, and the terminal mouth... > > > ! > > Above, Photo of Velvet Worm (Euperipatoides sp.) by Stephen Zozaya > > Aysheaia is believed to have grazed on prehistoric sponges gripping onto them with it's many claws. The shape of it's mouth suggests that it was a predator. It probably used the paired structures on it's head to grasp hold of its prey, and then pass it to the finger like projections around its mouth > > And now for some fossils! > > ! > > Above, Lobopodian Aysheaia pedunculata Walcott, 1911, USNM 365608 from the Stephen Formation (Cambrian Series 3, Stage 5), British Columbia, Canada here > > ! > > Above, Aysheaia pedunculata (ROM 61108). Complete specimen preserved laterally showing limbs and gut trace. Specimen length = 20 mm here > > ! > > Above, Aysheaia, a worm-like animal with annulated legs, from the Burgess Shale, Canada here > > Also this really awesome diorama of life under the Cambrian sea > > ! > > Above, Burgess Shale Biota (L-R) Aysheaia, annelid worms, Olenoides trilobite, Marrella here > > Well I hope you enjoyed this post (hopefully the first of many) of ancient invertebrates, and as usual my disclaimer that I'm not an expert, I just like sharing fun things! > > All information via wikipedia here and here, and not wikipedia from here and here

edit, formatting was a bit doolally

Many people assume that horses first came to the Americas when Spanish explorers brought them here about 500 years ago. In fact, recent research has confirmed a European origin for horses associated with humans in the American Southwest and Great Plains.

But those weren’t the first horses in North America. The family Equidae, which includes domesticated varieties of horses and donkeys along with zebras and their kin, is actually native to the Americas. The fossil record reveals horse origins here more than 50 million years ago, as well as their extinction throughout the Americas during the last Ice Age about 10,000 years ago.

cross-posted from: https://lemmy.dbzer0.com/post/16527542

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https://www.jurassiccoast.org/blog/read/2020/04/fools-gold-and-the-jurassic-coasts-missing-molluscs-b31

A 280-million-year-old fossil that has baffled researchers for decades has been shown to be—in part—a forgery, following new examination of the remnants.

The discovery has led the team, headed by Dr. Valentina Rossi of University College Cork, Ireland (UCC) to urge caution in how the fossil is used in future research.

Tridentinosaurus antiquus was discovered in the Italian Alps in 1931 and was thought to be an important specimen for understanding early reptile evolution. Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues. This led to its classification as a member of the reptile group Protorosauria.

66 million years ago, the last dinosaurs vanished from Earth. We're still trying to understand why. New fossils of abelisaurs—distant relatives of the tyrannosaurs—from north Africa suggest that African dinosaurs remained diverse up to the very end. And that suggests their demise came suddenly, with the impact of a giant asteroid.

The causes of the mass extinction have been debated for two centuries. Georges Cuvier, the father of paleontology, thought extinction was driven by catastrophes. Charles Darwin thought gradual changes in the environment and competition between species slowly drove lineages extinct.

Paleontology enthusiasts have unearthed one of the world's richest and most diverse fossil sites from the Lower Ordovician period (around 470 million years ago). Located in Montagne Noire, in the Hérault department of France, this deposit of over 400 fossils is distinguished by an exceptionally well-preserved fauna.

In addition to shelly components, it contains extremely rare soft elements such as digestive systems and cuticles, in a remarkable state of preservation. Moreover, this biota was once located very close to the South Pole, revealing the composition of Ordovician southernmost ecosystems.