Have paleontologists been praising it? Up to 95 percent of the hip joint reconstructions of pterosaurs and their distant relatives, dinosaurs more like birds, are anatomically impossible, according to new research that used a surprising source. But the conclusions of the study, counteracts an expert in pterosaurs, should be substantiated.
The development of an extinct animal only from the bones has always been the greatest challenge of paleontology, and mistakes have been made. But an article published today makes the bold claim that the field has had aspects of flight, specifically hip mobility, wrong for a long time.
The authors say they have developed a new way of mapping how pterosaurs and some dinosaurs may have taken wing. It all starts with the common quail.
The small bird may be better known for being heard and not seen, but researchers looked at it and apparently thought "hey, that's a good substitute for extinct ornithodirans".
Just about now it's worth reminding everyone that pterosaurs are not dinosaurs. Both pterosaurs and dinosaurs belong to the largest tribe of archosaurs, but so do birds (descendants of a lineage of dinosaurs) and crocodiles, archosaurs are still with us today. Archosaurs are typically divided into those of crocodile and birds, the latter group sometimes called ornithodirans, a term not fully accepted in the field.
In fact, there is much debate about which dead archosaurs fit where in the spectrum between the crocodile and the bird. For the purposes of this post, we will go with the definition of ornithodirans that the authors of today's document seem to use, which would include birds, dinosaurs and pterosaurs. (Although it is probably worth noting that the authors focus on maniraptors, dinosaurs more closely related to birds, rather than the entirety of Dinosauria.)
Meanwhile, pterosaurs, often called flying reptiles, They had enormous diversity only within their order. They spread from big as a bat to the famous Quetzalcoatlus, which was about the size of some airplanes.
Meanwhile, in Dinosaurland, there have been some non-bird species that are believed to be capable of some type of flight, either with motor or flight without motor, most notably Microraptor gui the "four-winged dinosaur" "From the Cretaceous, more than 120 million years ago. Researchers continue to debate about how the flight microraptors were, but that is another topic for another day.
Unlike birds (and closely related feathered dinosaurs that may have flown), pterosaurs evolved along a somewhat more path more like to a bat: Its wings were membranes attached to the elongated bones of the fingers. (In the bats, the membranes extend along the entire elongated "hand", but the pterosaur wings were joined to a single fourth super long finger.) Power Pinkie!)
So, to recap, the study Today he compares pterosaurs and some of the most bird-like dinosaurs, two different clans also very different from each other, to a quail.
About that quail …
While much of the research on all these winged animals focuses on the winged bits – the forelimbs – the authors behind the new study focus in the joints of the hip. They point out, correctly, that the joints are integrated systems of bone, cartilage, ligaments, muscles, tendons, nerves and blood vessels, of which only one remains in the fossil record: the bones, which only tell part of the history of a animal. .
By dissecting a handful of adult quail, the team isolated the various parts of the hip joint, bone and soft tissue, and then mapped the individual ranges of movement for each component, such as ligaments or bones. The authors were then able to superimpose different component maps, comparing their system with the countries and graphic continents. It can show, for example, the continent of Africa with topography or with political limits or with both.
What they found, according to the document, was that 94.72 percent of hip joint poses that are possible only by bones are in fact impossible when soft tissue restrictions are added, particularly the ligaments, which would have been present in the animal when it was alive.
Although the authors noted that some of the bone-only postures they tested were extreme and probably not to be included in a reconstruction, they add that the lack of "consistent methodological restrictions on hypothetical mobility" in the field does not mean that someone I did not try it. The "bat-like" hip expansion, for example, that has been proposed several times for pterosaurs and the Microraptor, is possible with quail bones, but not when their soft tissue limitations are included.
to a pterosaur is completely legitimate, the authors claim that the hip joints of birds, pterosaurs and maniraptoran dinosaurs (the dinosaurs included and more closely related to the birds, although there is disagreement over which species belong to this group) are "Similar in several aspects" Like the shape and positioning of the femoral head, or the upper part of the thigh.
I read the study a few times and, well, I had questions. Many of them, on their assumptions and conclusions. So I asked the paleontologist at the University of Leicester, David Unwin, a leading pterosaur expert not involved in the project, for his reaction to the document.
"On the positive side, the new data is always useful, and the basic focus of this study seems to be fine," Unwin responded by email. "Understanding the anatomy / function of birds (alive) and applying it to extinct birds / bird-like dinosaurs is reasonable, although the potential limitations of this approach require much more analysis than that given in this document"
] That's the good news.
"The pterosaur component of this document is clearly strange, it feels like it is connected later and in many ways it is very defective," Unwin said.
For example, Unwin continued, the bone structure around the hip joint, the pelvis and the femur, is completely different for pterosaurs and birds. as several previous studies not mentioned in today's document have established. A recent study specifically on the musculature of the pterosaur pelvis is also ignored. Unwin was added: " There is no reason to assume, therefore, that … the ligaments and soft tissues of the joints of pterosaurs and birds of the hip are comparable, in which case the arguments presented by the authors on the limitations of soft tissue in the orientation of the pterosaurio femur is not valid. "
Unwin described the approach of the authors as" puzzling ", including their use of the 1817 pterodactylus juvenile illustration (which is seen at the top of this publication), which was discarded long ago because it is inaccurate. "The authors repeatedly refer to a 'bat pose' for the hind limbs of pterosaurs, why, this idea was abandoned decades ago," he added.
There were other omissions, said Unwin. The authors do not recognize the debate on whether even pterosaurs were ornithodirans, nor do they address the hundreds of fossils – and thousands of pterosaur tracks – that contradict the study's conclusions.
"In general, the article seems completely out of date with respect to pterosaurs, using a terminology and understanding that seem to take root in the 1980s," Unwin concluded. "Much more fossil material has been found in the last 35 years and ideas have advanced a lot, this document does not, in fact, one might ask why pterosaurs were included in this document at all?"
diamond in wavy feathers
As in any field of science, in paleontology, hypotheses are tested and revised and, finally, consensus emerges. Even consensus can be eliminated and rewritten if a sufficient and credible counter-evidence appears.
But today's study is not going to rewrite any textbook. It offers a new way to map the potential ranges of mobility of an extinct animal, a method that can, once again extensively tested with a variety of proxies, provide a more accurate and detailed picture of how the animal actually moved. And that would be a great addition to the paleontologist's toolkit.
The true value of the investigation is buried, however, in a strange refutation of antiquated ideas refuted long ago, and a curious creak of disparate animals.
As any eight year old child can tell you, Quetzalcoatlus was not a greed.
The study appears in Proceedings of the Royal Society B: Biological Sciences .