Jurassic sauropod dinosaur, from quadrupedal to bipedal


GROWING UP As Mussaurus patagonicus grew, the long-necked dinosaur’s center of mass shifted back toward its hips and tail, letting it go from a four-legged to two-legged gait even as it ballooned from the size of a chick to that of a rhinoceros. A. Otero et al./Scientific Reports 2019

By John Pickrell, 5:00am, May 20, 2019:

This early sauropod went from walking on four legs to two as it grew

Center of mass shifts led to a rare change in walking style for a long-necked dinosaur relative

Most long-necked sauropods lumbered on four legs all their lives to support their titanic bulk. But an early relative of such behemoths as Brachiosaurus made the unusual transition from walking on four legs to two as it grew, a new study shows.

Diminutive at hatching, Mussaurus patagonicus (which means “mouse lizard”) began life walking on all fours. But by the time the 200-million-year-old plant eater reached its 6-meter-long adult size, it roamed what’s now Argentina on two legs.

The changing length of M. patagonicus’s arm bones relative to its body and its inward facing-palms as an adult had hinted at the transition. But for the first time, computer simulations based on a rich fossil record show how a shift in the creature’s center of gravity as it grew enabled a change to bipedal walking, researchers report May 20 in Scientific Reports.

Researchers took CT scans of fossil bones from six individual M. patagonicus — covering different stages of the species’ development, from 60-gram hatchlings the size of baby chickens to 1.5 metric ton adults the size of rhinoceroses. The researchers added virtual flesh to digitized bones to create 3-D models that allowed them to estimate both the weight and center of gravity of M. patagonicus at many different stages of its life.

Reconstructions of the hatchlings showed that the creature’s center of mass was so far forward that the dinosaurs could move around only by walking on all four legs, says Andrew Cuff, a paleontologist of the Structure and Motion Laboratory of the Royal Veterinary College in Hatfield, England.

As the dinos grew, their center of mass moved back toward their hips, allowing them to walk upright on two legs, Cuff and colleagues found. The transition “is incredibly rare,” he says. “We have struggled to find any other animals aside from humans that go through that transition…. Finding it in the fossil record is pretty exceptional.”

The results suggest these adult dinosaurs turned bipedal because their tail muscles became bulkier and heavier as they grew, moving their center of gravity backward, says Stephen Poropat, a paleontologist at Swinburne University of Technology in Melbourne, Australia, who was not involved in the research. “It is not the changing proportions of Mussaurus’s front legs that is necessitating this change from walking on four legs to walking on two legs as an adult,” he says.

As later long-necked dinos bulked up in size (SN Online: 9/4/14), going to two legs may no longer have been an option. Massive sauropods instead probably started on four legs like M. patagonicus and stayed that way, developing trunklike front legs to bear their weight. “What we gain from this [study] is that there may be a size limit of how big you can get being a biped in this group,” Cuff says.

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Jurassic bird species discovery, second ever


Alcmonavis fossil

From the Ludwig-Maximilians-Universität München in Germany:

First birds: Archaeopteryx gets company

May 14, 2019

Summary: Researchers describe a hitherto unknown bird from the late Jurassic period. It is the second bird capable of flight, after the famous Archaeopteryx, to be identified from this era.

Archaeopteryx’s throne is tottering. Since the discovery of the first fossil of the primal bird in 1861, it had been considered the only bird from the Jurassic geological period. Today’s birds are thought to be direct descendants of carnivorous dinosaurs, with Archaeopteryx representing the oldest known flying representative of this lineage. All of the specimens that have been found up to now come from the region of the Solnhofen Archipelago, which during the Jurassic era spanned across what is today the Altmühl Valley, in the area between Pappenheim and Regensburg. Archaeopteryx lived here in a landscape of reef islands about 150 million years ago.

A team led by Professor Oliver Rauhut has taxonomically identified a bird unknown until now: Alcmonavis poeschli, the second bird from the era identified as capable of flight. “This suggests that the diversity of birds in the late Jurassic era was greater than previously thought,” says Rauhut, paleontologist at the Department of Earth and Environmental Sciences as well as the Bavarian State Collection of Paleontology and Geology.

Only a wing of Alcmonavis poeschli was discovered. “At first, we assumed that this was another specimen of Archaeopteryx. There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird,” says Rauhut. According to the team’s taxonomic studies, which are currently featured in the scientific journal eLife, Alcmonavis poeschli was not merely somewhat larger than Archaeopteryx; apparently it could also fly better. “The wing muscles indicate a greater capacity for flying,” says Rauhut. Alcmonavis poeschli exhibits numerous traits lacking in Archaeopteryx but present in more recent birds. This suggests that it was adapted better to active, flapping flight.

The discovery of Alcmonavis poeschli has implications for the debate over whether active flapping birds arose from gliding birds. “Its adaptation shows that the evolution of flight must have progressed relatively quickly,” says Dr. Christian Foth from the University of Fribourg (Switzerland), one of the co-authors of the study.

The bird now being described for the first time derives its name from the old Celtic word for the river Altmühl, Alcmona, and its discoverer Roland Pöschl, who leads the excavation at the Schaudiberg quarry close to Mörnsheim. A fossil of Archaeopteryx was also discovered in the same unit of limestones. The two primal birds thus apparently lived at the same time in what was then a subtropical lagoon landscape in southern Germany.

Jurassic crocodile discovery in Germany


This 4 April 2019 video is called Primitive crocodile that roamed prehistoric seas 150 million years ago unearthed.

From the University of Edinburgh in Scotland:

Jurassic crocodile discovery sheds light on reptiles’ family tree

April 4, 2019

Summary: A 150 million-year-old fossil has been identified as a previously unseen species of ancient crocodile that developed a tail fin and paddle-like limbs for life in the sea.

A newly identified species of 150 million-year-old marine crocodile has given insights into how a group of ancient animals evolved.

The ancestor of today’s crocodiles belonged to a group of animals that developed a tail fin and paddle-like limbs for life in the sea, resembling dolphins more than crocodiles.

These slender animals, which fed on fast-moving prey such as squid and small fish, lived during the Jurassic era in shallow seas and lagoons in what is now Germany. Related species have previously been found in Mexico and Argentina.

An international team of scientists, including researchers from Germany and the University of Edinburgh, identified the new species from a remarkably well-preserved skeleton.

The fossil was discovered in 2014 in a quarry near the town of Bamberg in Bavaria, Germany by a team from the Naturkunde-Museum Bamberg, where it is now housed. The species, Cricosaurus bambergensis, takes its name from the town.

Researchers compared the fossil with those from other museum collections, and confirmed that it was a previously unseen species.

The skeleton has several distinguishing features in its jaws, the roof of its mouth and tail, some of which have not been seen in any other species.

Experts created digital images of the fossil in high resolution, to enable further research. They expect the fossil will aid greater understanding of a wider family of ancient animals, known as metriorhynchid, to which this species belonged.

The research, carried out with Naturkunde-Museum Bielefeld, Eberhard-Karls Universität Tübingen and commercial partners Palaeo3D, is published in Acta Palaeontologica Polonica.

Dr Mark Young, of the University of Edinburgh’s School of GeoSciences, who took part in the study, said: “The rock formations of southern Germany continue to give us fresh insights into the age of dinosaurs. These rock layers were deposited at a time when Europe was covered by a shallow sea, with countries such as Germany and the UK being a collection of islands.”

Sven Sachs, from the Naturkunde-Museum Bielefeld, who led the project, said: “The study reveals peculiar features at the palate that have not been described in any fossil crocodile so far. There are two depressions which are separated by a pronounced bar. It is not clear what these depressions were good for.”

Jurassic dinosaurs excavation in Wyoming, USA


This 26 March 2019 video about the USA says about itself:

The Natural History Museum [in London, England] has joined an international partnership, called Mission Jurassic, to excavate a new Jurassic site. The project is named after an area known as the ‘Jurassic Mile’ in Wyoming, which has many Jurassic dinosaur and fish fossils, trackways and fossilised plants.

NHM is working with The Children’s Museum of Indianapolis and the Naturalis Biodiversity Center in Leiden, Netherlands on the US dinosaur dig, the UK museum’s first major overseas dig since the 1980s.

Translated from Leidsch Dagblad daily in the Netherlands, 25 March 2019:

Naturalis Biodiversity Center in Leiden returns to Wyoming. Together with two other natural history museums, the Natural History Museum in London and the Children’s Museum in Indianapolis, Naturalis is going to dig up in the United States at least two long-necked dinosaurs. The Leiden museum previously found the well-known T. rex “Trix” in Montana and five Triceratops in Wyoming.

Countless bones, fossils and footprints of the largest dinosaurs that have ever lived come together on the Wyoming site. “We hope to learn a lot about biodiversity in the Jurassic at this place”, says paleontologist and team leader Anne Schulp. “This was the period of the well-known long-necked dinosaurs such as Brachiosaurus and Diplodocus. We go back some 150 million years in this excavation. That is far before the Tyrannosaurus rex that now shows off in the museum.”

… The location has been known for some time. The Children’s Museum started the first trial excavations two years ago. That has since produced the first bones of two long-necked dinosaurs.

Naturalis, which will reopen at the end of the summer, has a “dinosaur hall” in the new building dedicated to the Jurassic era (201-145 million years ago). The museum already has a skeleton of a long-necked dinosaur from that period in its collection for that hall. That is a Camarasaurus, but, says Schulp, “it is a small one at 17 meters.”

Archaeopteryx feather not Archaeopteryx feather


This 2016 video says about itself:

Archeopteryx had strong feathers, bony jaws and teeth, and a tail with a line of bone running down its legs. Physically, it was exactly half-reptile, half-bird.

From The University of Hong Kong:

First discovered fossil feather did not belong to iconic bird Archaeopteryx

Imaging technology shows first discovered fossil feather did not belong to iconic bird Archaeopteryx

February 4, 2019

A 150-year-old fossil feather mystery has been solved by an international research team including Dr Michael Pittman from the Department of Earth Sciences, The University of Hong Kong. Dr Pittman and his colleagues applied a novel imaging technique, Laser-Stimulated Fluorescence (LSF), revealing the missing quill of the first fossil feather ever discovered, dethroning an icon in the process.

This fossil feather was found in the Solnhofen area of southern Germany in 1861. The isolated feather was used to name the iconic fossil bird Archaeopteryx and was closely identified with its skeletons. Unlike the feather impressions preserved in some Archaeopteryx fossils, the isolated feather is preserved as a dark film. The detailed 1862 description of the feather mentions a rather long quill visible on the fossil, but this is unseen today. Even recent x-ray fluorescence and UV imaging studies did not end the debate of the “missing quill.” The original existence of this quill has therefore been debated and it was unclear if the single feather represented a primary, secondary, or primary covert feather.

The results of this study are described in the journal Scientific Reports, and underscore the potential and scientific importance of Laser-Stimulated Fluorescence, which is being developed by Thomas G Kaye of the Foundation for Scientific Advancement, USA and Dr Pittman. “My imaging work with Tom Kaye demonstrates that important discoveries remain to be made even in the most iconic and well-studied fossils,” says Dr Pittman.

With the help of the LSF images, the team finally solved the 150-year-old missing quill mystery. The now completely visible feather allowed detailed comparisons with the feather impressions of Archaeopteryx and with living birds. Before this LSF work, the feather was thought to represent a primary covert from Archaeopteryx, but this study shows that it differs from coverts of modern birds by lacking a distinct s-shaped centerline. The team also ruled out that the feather represented a primary, secondary, or tail feather of Archaeopteryx. Instead, the new data indicates that the isolated feather came from an unknown feathered dinosaur and that its attribution to Archaeopteryx was wrong. “It is amazing that this new technique allows us to resolve the 150-year-old mystery of the missing quill,” says Daniela Schwarz, co-author in the study and curator for the fossil reptiles and bird collection of the Museum für Naturkunde, Berlin. This discovery also demonstrates that the diversity of feathered dinosaurs was likely higher around the ancient Solnhofen Archipelago than previously thought. “The success of the LSF technique here is sure to lead to more discoveries and applications in other fields. But, you’ll have to wait and see what we find next!” added Tom Kaye, the study’s lead author.

How sauropod dinosaurs moved, new study


This video is called Sauropod OviparityWalking With Dinosaurs – BBC.

From the University of Bonn in Germany:

Long-necked dinosaurs rotated their forefeet to the side

Scientists investigated the tracks of sauropods

January 29, 2019

Long-necked dinosaurs (sauropods) could orient their forefeet both forward and sideways. The orientation of their feet depended on the speed and centre of mass of the animals. An international team of researchers investigated numerous dinosaur footprints in Morocco at the foot of the Atlas Mountains using state-of-the-art methods. By comparing them with other sauropod tracks, the scientists determined how the long-necked animals moved forward. The results have now been published in the Journal of Vertebrate Paleontology.

“Long-necked dinosaurs” (sauropods) were among the most successful herbivores of the Mesozoic Era — the age of the dinosaurs. Characteristic for this group were a barrel-shaped body on columnar legs as well as an extremely long neck, which ended in a relatively small head. Long-necked dinosaurs existed from about 210 to 66 million years ago — they thus had been able to assert themselves on earth for a very long period. Also their gigantism, with which they far surpassed other dinosaurs, points at their success.

Sauropods included the largest land animals in Earth history, some over 30 metres long and up to 70 tonnes in weight. “However, it is still unclear how exactly these giants moved,” says Jens Lallensack, paleontologist at the Institute of Geosciences and Meteorology at the University of Bonn in Germany. The limb joints were partly cartilaginous and therefore not fossilised, allowing only limited conclusions about the range of movement.

Detective work with 3D computer analyses

The missing pieces of the puzzle, however, can be reconstructed with the help of fossil footprints of the giants. An international team of researchers from Japan, Morocco and Germany, led by the University of Bonn, has now investigated an unique track site in Morocco at the foot of the Atlas Mountains. The site consists of a surface of 54 x 6 metres which was vertically positioned during mountain formation and shows hundreds of individual footprints, some of which overlap. A part of these footprints could be assigned to a total of nine trackways (sequences of individual footprints). “Working out individual tracks from this jumbled mess of footprints was detective work and only possible through the analysis of high-resolution 3D models on the computer,” says Dr. Oliver Wings of the Zentralmagazin Naturwissenschaftlicher Sammlungen der Martin-Luther-Universität Halle-Wittenberg in Germany.

The researchers were amazed by the results: the trackways are extremely narrow — the right and left footprints are almost in line. Also, the forefoot impressions are not directed forwards, as is typical for sauropod tracks, but point to the side, and sometimes even obliquely backwards. Even more: The animals were able to switch between both orientations as needed. “People are able to turn their palms downwards by crossing the ulna and radius,” says Dr. Michael Buchwitz of the Museum für Naturkunde Magdeburg. However, this complicated movement is limited to mammals and chameleons in today’s terrestrial vertebrates. It was not possible in other animals, including dinosaurs. Sauropods must therefore have found another way of turning the forefoot forwards.

How can the rotation of the forefoot be explained?

How can the rotation of the forefoot in the sauropod tracks be explained? The key probably lies in the mighty cartilage layers, which allowed great flexibility in the joints, especially in the shoulder. But why were the hands rotated outwards at all? “Outwardly facing hands with opposing palms were the original condition in the bipedal ancestors of the sauropods,” explains Shinobu Ishigaki of the Okayama University of Science, Japan. The question should therefore be why most sauropods turned their forefeet forwards — an anatomically difficult movement to implement.

A statistical analysis of sauropod tracks from all over the world could provide important clues: Apparently the animals tended to have outwardly directed forefeet when the foreleg was not used for active locomotion but only for carrying body weight. Thus the forefeet were often rotated further outwards when the animal moved slowly and the centre of mass of the body was far back. Only if the hands were also used for the forward drive, a forefoot directed to the front was advantageous. The analysis furthermore showed that the outer rotation of the forefeet was limited to smaller individuals, whereas in larger animals they were mostly directed forward. The large animals apparently could no longer rotate their forefeet sideways. “This loss of mobility was probably a direct result of their gigantism,” says Lallensack.