This Adaptation Allowed Dinosaurs to Not Only Survive But to Dominate The Planet

NATURE18 March 2023

BySALLY CHRISTINE REYNOLDS, THE CONVERSATION

(Leonekki Calvetti/Science Photo Library/Getty Images)

It's sometimes difficult to imagine how the planet we call home, with its megalopolis cities and serene farmlands, was once dominated by dinosaurs as big as buses and five-story buildings.

But recent research has helped deepen our understanding of why dinosaurs prevailed: the answer may lie in their special bones, structured like Aero chocolate.

Brazilian paleontologist Tito Aureliano found that hollow bones filled with little air sacs were so important to dinosaur survival, they evolved independently several times in different lineages.

According to the study, aerated bones evolved in three separate lineages: pterosaurs, technically flying reptiles, and two dinosaur lineages, theropods (ranging from the crow-sized Microraptor to the huge Tyrannosaurus rex) and sauropodomorphs (long-necked herbivores including Brachiosaurus).

The researchers focused on the late Triassic period, roughly 233 million years ago, in south Brazil.

Every time an animal reproduces, evolution throws up random variants in genetic code. Some of these variants are passed on to offspring and develop over time.

Charles Darwin believed evolution created "endless forms most beautiful". But some adaptations emerge spontaneously time and time again, a bit like getting the same hand of cards on multiple occasions.

When the same hand keeps cropping up, it's a sign that evolution has hit upon an important and effective solution.

The variant the Brazilian team studied was aerated vertebrae bones, which would have enhanced the dinosaurs' strength and reduced their body weight.

Light but mighty

Your regular deliveries from Amazon or other online retailers come packed in corrugated cardboard, which has the same advantages as aerated bones. It is light, yet tough.

Corrugated cardboard, or as it was first known, pleated paper, was a man-made design experiment that was hugely successful and is now part of our everyday lives. It was patented in England in 1856 and was initially designed to support top hats, which were popular in Victorian England and the US at the time.

Three years later, Darwin published his On the Origin of Species which outlined how evolutionary traits that create advantages are more likely to be passed on to future generations than variants which don't.

CT scan technology allowed Aureliano and his colleagues to peer inside the rock-hard fossils they studied. Without the modern technology, it would have been impossible to look inside the fossils and detect the air sacs in the spinal columns.

The study found no common ancestor had this trait. All three groups must have developed air sacs independently, and each time in slightly different ways.

The air sacs probably enhanced oxygen levels in the dinosaurs' blood. The Triassic period had a scorching hot and dry climate. So more oxygen circulating in the blood would cool dinosaur bodies more efficiently. It would also allow them to move faster.

The air sacs would have buttressed and reinforced the internal structure of the dinosaurs' bones while creating a greater surface area of attachments for large, powerful muscles.

This would have enabled the bones to grow to a far larger size without weighing the animal down.

In living birds, aerated bones reduce overall mass and volume, while enhancing bone strength and stiffness – essential features for flight.

Paleontology not only tells the story of what might have been for Earth, had it not been for that infamous asteroid, but also helps us learn about the evolution of still living creatures.

Prehistoric connections

Echoes of this dinosaur legacy lie in many animals alive today. It is not only long-dead animals which found this type of adaptation useful. Many bird species living today rely on hollow bones to fly.

Others animals use the air sacs to buttress and strengthen their large bones and skulls, without weighing them down.

An excellent example of this is the elephant skull. Inside elephant skulls are large air sacs which allow the animal to move its massive head and heavy tusks without straining the neck muscles.

The human brain is also protected by two layers of hard, compact, bone (inner and outer tables) which sandwich a layer of softer, spongey, and aerated bone in between, known as the diploe. This allows our skulls to be light, but strong and able to absorb shocks to cranium.

These are examples of convergent evolution in which animals are faced repeatedly with the same problem, evolving similar – but not always identical – solutions each time. Animals today are playing by the same evolutionary playbook as the dinosaurs.

Sally Christine Reynolds, Principal Academic in Hominin Palaeoecology, Bournemouth University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This Dinosaur Had a 50-Foot-Long Neck, Scientists Say

They compared vertebrae discovered in 1987 to more complete remains to make this new estimate

Will Sullivan

March 17, 2023

A rendering of Mamenchisaurus sinocanadorum dinosaurs with

 their 50-foot-long necks. Júlia d’Oliveira

A dinosaur that roamed East Asia 162 million years ago had an impressive, 50-foot-long neck, according to a new paper published Wednesday in the Journal of Systematic Paleontology.

The creature, called Mamenchisaurus sinocanadorum, belonged to a group called sauropods. These large, plant-eating dinosaurs are known for their lengthy necks and tails—but, according to the scientists’ estimate, Mamenchisaurus had the longest neck of them all.

Researchers uncovered the dinosaur’s fossilized remains in China in 1987, but they didn’t have much of the creature to study—only a few bones, including some vertebrae and a rib, writes New Scientist’s Chris Stokel-Walker.

Still, the scientists estimated the length of the dinosaur’s neck by comparing the limited evidence to more complete skeletons of its relatives. They looked at the 44-foot-long neck of a sauropod called Xinjiangtitan, which was discovered in 2013 and is the longest complete neck ever found, according to the New York Times’ Jack Tamisiea.

“Our analyses make us fairly confident that Mamenchisaurus sinocanadorum had 18 vertebrae in its neck, because close cousins known from more complete skeletons all have 18 cervical vertebrae,” Andrew Moore, a co-author of the study and a paleontologist at Stony Brook University, told Live Science’s Laura Geggel in an email. “So, focusing just on these close relatives with similar necks, we scaled up.”

The researchers determined that the Mamenchisaurus’ neck was approximately 49.5 feet long, per a statement. Such a length would have come in handy for foraging—the creatures could efficiently graze large amounts of vegetation, Moore tells Live Science.

“The long necks of these animals are amazing, even by dinosaur standards,” David Hone, a paleontologist who studies dinosaurs at Queen Mary University of London and was not involved in the research, tells New Scientist. “Understanding their evolution is really important to see how these animals lived.”

The dinosaurs evolved a few ways to manage their unwieldy necks. Researchers used CT scans to find that most of the vertebrae’s volume—about 69 to 77 percent—was air, similar to the vertebrae of some birds. Such air-filled bones would be lighter, making it easier for the Mamenchisaurus to hold up its giant neck, per the statement.

“Having such a long neck is a large weight that you have to position away from your body,” Cary Woodruff, a paleontologist at the Frost Science Museum who studies sauropods and did not contribute to the paper, tells the New York Times. “If you have to hold a hammer with your arm stretched out, your arm’s going to get tired pretty quick.”

For added support, the dinosaur had 13-foot-long ribs that would have made its neck more stable and less prone to injury, according to the statement. It also held its neck at a relatively shallow angle of 20 to 30 degrees.

“The long-necked dinosaurs evolved their own, different ways of coping with giantism and supporting long necks, and there are numerous amazing deposits with long-necked sauropods across China,” Natalia Jagielska, a paleontologist at the University of Edinburgh in Scotland who didn’t contribute to the research, tells New Scientist.

Oldest fossils of remarkable marine reptiles found in Arctic

The researchers had thought any ichthyosaur living 250 million years ago would have been a primitive form, not far removed from its land-living forerunners. The fossils showed this one, which has not yet been given a scientific name, was quite advanced anatomically.

By: Reuters
Washington | Updated: March 16, 2023 

An artist's reconstruction shows the earliest-known Ichthyosaur, along with other marine creatures in the 250-million-year-old ecosystem found on the remote Arctic island of Spitsbergen, Norway, in this undated handout image obtained by Reuters on March 14, 2023.

Ichthyosaurs were a successful group of marine reptiles that prospered during the age of dinosaurs, some reaching up to around 70 feet (21 meters) long – exceeded in size in the history of Earth’s oceans only by the largest of the whales.

But their origins have been a bit mysterious. Fossils dating to about 250 million years ago unearthed in a harsh and remote locale – Norway’s Arctic island of Spitsbergen – are now providing surprising insight into the rise of ichthyosaurs.

Researchers said they found remains of the earliest-known ichthyosaur, which lived approximately 2 million years after Earth’s worst mass extinction that ended the Permian Period, wiping out roughly 90% of the planet’s species amid massive Siberian volcanism. The 11 tail vertebrae discovered indicate that the animal was about 10 feet (3 meters) long, making it a top predator.

Like whales, which are mammals, and the various other reptile lineages that have inhabited Earth’s oceans, ichthyosaurs evolved from ancestors that walked on land and underwent a land-to-sea transition.

The researchers had thought any ichthyosaur living 250 million years ago would have been a primitive form, not far removed from its land-living forerunners. The fossils showed this one, which has not yet been given a scientific name, was quite advanced anatomically.

“The real surprise was that after a suite of geochemical, computerized micro-tomographic and bone microstructural analyses, the vertebrae turned out to be from a highly advanced, fast-growing, probably warm-blooded, large-bodied at around 3 meters long, and fully oceanic ichthyosaur,” said Benjamin Kear, curator of vertebrate palaeontology at Uppsala University’s Museum of Evolution in Sweden and lead author of the research published in the journal Current Biology.

“The implications of this discovery are manifold, but most importantly indicate that the long-anticipated transitional ichthyosaur ancestor must have appeared much earlier than previously suspected,” Kear added.

 

A computed tomography image and cross-section shows the internal bone structure of vertebrae from the earliest-known Ichthyosaur, a type of marine reptile that flourished during the age of dinosaurs. Oyvind Hammer and Jorn Hurum/Handout via REUTERS

In light of this discovery, it may be that ichthyosaur origins predated the mass extinction event by up to perhaps 20 million years, Kear said.

The Triassic Period that followed the mass extinction was the opening act of the age of dinosaurs, though the oldest-known dinosaurs did not appear until about 230 million years ago.

The site where the fossils were found is a classic Arctic landscape with high snow-capped mountains along the coast of a deep fjord. The fossils were exposed along a river channel fed by snow melt that cuts through rock layers that were once mud at the bottom of the sea. While today there are polar bears and beluga whales at Spitsbergen, 250 million years ago the sea there would have been teeming with fish, sharks, shelled squid-like ammonoids and crocodile-like marine amphibians called temnospondyls.

The mass extinction shook up land and marine ecosystems and opened opportunities for new species to fill ecological roles vacated by extinct creatures. Ichthyosaurs quickly became dominant and endured until about 90 million years ago.

Many ichthyosaurs looked like dolphins, except with vertical rather than horizontal tail flukes. Others resembled large whales. The biggest included Shastasaurus, at about 70 feet (21 meters). They ate fish and squid. Fossils show ichthyosaurs giving live birth to their young.

Until now, the oldest-known member of the ichthyosaur lineage was a 16-inch-long (40-cm-long) creature called Cartorhynchus that lived 248 million years ago in China.

Researchers in recent decades have identified the earliest forms of whales, including one called Ambulocetus, dubbed the “walking whale” because it retained limbs that enabled it to still move around on land.

“Most excitingly, the mysterious ‘walking’ ichthyosaur ancestor is undoubtedly still out there waiting to be uncovered,” Kear said. “Only now we will have to start looking in even older rocks, which is exactly what we will be doing on our next fossil-hunting trip to Spitsbergen this summer.”

First published on: 15-03-2023

Fossil Friday: The Abrupt Origin of Ichthyosaurs

Günter Bechly

March 17, 2023

,.

Photo credit: H. Zell, CC BY-SA 3.0 , via Wikimedia Commons

This Fossil Friday features Stenopterygius quadricissus from the Lower Jurassic Posidonia shale of Holzmaden in southern Germany, which is about 190 million years old. As a child I went collecting fossils from this fossil locality, which was close to my childhood home, and with a bit of luck you could not only find ammonites but even vertebrae of such ichthyosaurs. Apart from dinosaurs and pterosaurs, the ichthyosaurs are one of the iconic groups of Mesozoic reptiles. Even though they look like a hybrid between a dolphin and a shark, they were marine reptiles that are believed to have descended from monitor-lizard-like terrestrial ancestors.

Darwinism would predict a long and gradual transition between these very different body plans, but actually ichthyosaurs appeared very abruptly about 4 million years after the great end-Permian mass extinction event about 252 million years ago, which annihilated about 81 percent of marine and 70 percent of terrestrial biodiversity. There is general consensus that ichthyosaurs did not yet exist before this cataclysm, and the oldest fossils indeed only appeared in the Lower Triassic of China about 248 million years ago. Jiang et al. (2016) concluded that “ichthyosauriforms evolved rapidly within the first one million years of their evolution.” Well, that was the state of knowledge until a few days ago, when a brand new study (Kear et al. 2023) changed the picture and made the origin of ichthyosaurs even much more abrupt. A team of scientists from Norway and Sweden described ichthyosaur remains from the Arctic island of Spitsbergen, which are about 250 million years old but already show clear evidence for a fully marine way of life.

Revealing Admissions

The press release by Uppsala University (2023) makes some very revealing admissions about this unexpected discovery:

As the story goes, land-based reptiles with walking legs invaded shallow coastal environments to take advantage [of] marine predator niches that were left vacant by this cataclysmic event. Over time, these early amphibious reptiles became more efficient at swimming and eventually modified their limbs into flippers, developed a fish-like body shape, and started giving birth to live young; thus, severing their final tie with the land by not needing to come ashore to lay eggs.

The new fossils discovered on Spitsbergen are now revising this long accepted theory. …

Unexpectedly, these vertebrae occurred within rocks that were supposedly too old for ichthyosaurs. Also, rather than representing the textbook example of an amphibious ichthyosaur ancestor, the vertebrae are identical to those of geologically much younger larger-bodied ichthyosaurs, and even preserve internal bone microstructure showing adaptive hallmarks of fast growth, elevated metabolism and a fully oceanic lifestyle.

This means nothing less than that the transition from a land-living reptile to a fish-like marine reptile was completed in less than 2 million years, which corresponds to about half the average longevity of a larger vertebrate animal species. This is incredibly short in geological and biological terms and does not allow for the required genetic changes to have originated by an unguided process. This waiting time problem of neo-Darwinism is proven by population genetic calculations, which is the subject on an ongoing research project by Discovery Institute scientists.

Even the time span of 4 million years that was implied by the previously known fossil record of Early Triassic ichthyosaurs is shockingly short, so much so that a friend and colleague of mine, who is a renowned expert on ichthyosaurs and neither a theist nor an advocate of intelligent design, confidentially told me that he came to doubt the neo-Darwinian explanation for this very reason. He said: “That this transition happened by a Darwinian mechanism in such a short time is simply IMPOSSIBLE!” With this window of time now cut in half, the transition becomes even more incredible.

A Temporal Paradox

But there is another problem: The new discovery makes fully marine ichthyosaurs older than their alleged amphibious relatives such as Cartorhynchus (Motani et al. 2015, Jiang et al. 2016) and likely older than their unknown terrestrial relatives. This creates a temporal paradox of assumed descendants appearing before their assumed stem group. Thus, ichthyosaurs joined the numerous other examples of such paradoxes, such as early tetrapods or early birds. Not exactly a success story for Darwinism.

With increasing knowledge of the fossil record, the mainstream narrative is rendered more and more untenable and inconsistent with the empirical evidence. It’s time to move on and consider more adequate explanations like intelligent design theory.

References

• Jiang DY, Motani R, Huang JD et al. 2016. A large aberrant stem ichthyosauriform indicating early rise and demise of ichthyosauromorphs in the wake of the end-Permian extinction. Scientific Reports 6: 26232, 1–9. DOI: https://doi.org/10.1038/srep26232 
• Kear BP,  Engelschiøn VS, Hammer Ø, Roberts AJ & Hurum JH 2023. Earliest Triassic ichthyosaur fossils push back oceanic reptile origins. Current Biology 33(5), 178–179. DOI: https://doi.org/10.1016/j.cub.2022.12.053
• Motani R, Jiang DY, Chen GB et al. 2015. A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature 517, 485–488. DOI: https://doi.org/10.1038/nature13866
• Uppsala University 2023. Oldest sea reptile from Age of Dinosaurs found on Arctic island. Phys.org March 13, 2023. https://phys.org/news/2023-03-oldest-sea-reptile-age-dinosaurs.html

A Unique Window Into the Past – Ancient Jurassic Shark Fossil Reveals Surprising Evolutionary Truth

By UNIVERSITY OF VIENNA MARCH 16, 2023

Fossil of the Late Jurassic shark Protospinax annectans from Solnhofen and Eichstätt, Germany. Credit: Sebastian Stumpf

The evolutionary history of sharks and rays has been illuminated by a recently constructed phylogenetic tree.

A recent study by an international team of researchers, led by paleobiologist Patrick L. Jambura from the University of Vienna’s Department of Palaeontology, has revealed that cartilaginous fish have undergone more evolutionary changes than previously thought. The evidence for this conclusion was obtained from new fossils of a shark-like ray called Protospinax annectans, which show that sharks were highly evolved during the Late Jurassic period. The findings of the study have been published in the journal Diversity.

Sharks, rays, and ratfish are a group of ancient animals known as cartilaginous fishes, which have been present on earth for over 400 million years, predating the dinosaurs. They have also endured all five mass extinctions and their fossil remains can be found globally in great quantities. However, typically only their teeth remain intact as the cartilaginous skeleton decays along with the rest of the body and does not fossilize.

A unique window into the past

In the Solnhofen archipelago, a so-called “Konservat Lagerstätte” in Bavaria, Germany, skeletal remains and even imprints of skin and muscles of Late Jurassic vertebrates (including cartilaginous fishes) have been preserved due to special preservation conditions. The research team used this circumstance to take a closer look at the previously unclear role of the already extinct species Protospinax annectans in the evolution of sharks and rays, also with the help of modern genetic evidence.

Paleoreconstruction of the Solnhofen Archipelago 150 million years ago showing Protospinax annectans and the Jurassic ray Asterodermus platypterus. Credit: Manuel Andreas Staggl

“Protospinax carried features that are found in both sharks and rays today,” explains study author Patrick L. Jambura. Protospinax lived some 150 million years ago and was a 1.5-m-long, dorso-ventrally flattened cartilaginous fish with expanded pectoral fins and a prominent fin spine in front of each dorsal fin. Although known from well-preserved fossils, the phylogenetic position of Protospinax has puzzled researchers ever since it was first described in 1918

“Of particular interest,” Jambura continued, “is whether Protospinax represents a transition between sharks and rays as a ‘missing link’ — a hypothesis that has gained considerable appeal among experts over the past 25 years.”

 Alternatively, Protospinax could have been a very primitive shark, an ancestor of rays and sharks, or an ancestor of a certain group of sharks, the Galeomorphii, which includes the great white shark today — all of which are exciting ideas whose plausibility has now been clarified by scientists.

One mystery solved, another one remains

Incorporating the latest fossil finds, Jambura and his international team reconstructed the family tree of extant sharks and rays using genetic data (mitochondrial DNA) and embedded fossil groups — including Protospinax annectans — using morphological data. The results of the analysis were startling: Protospinax was neither a “missing link” nor a ray nor a primitive shark — but a highly evolved shark.
“We tend to think of evolution like a hierarchical, ladder-like system, in which older groups are at the base, while humans, as a very young species in Earth’s history, are at the top. In truth, however, evolution has never stopped even for these primitive representatives, but they continue to evolve day by day via changes in their DNA, just as we do. This is the only way they have been able to adapt to constantly changing environments and survive to this day,” says Jambura.

Even though cartilaginous fishes as a group have survived to this day, most species disappeared during their evolution, including Protospinax. Why Protospinax became extinct at the Jurassic-Cretaceous boundary some 145 million years ago and why there are no comparable shark species today, while the ecologically similarly adapted rays exist relatively unchanged to this day, remains a mystery at this point.

Reference: “Systematics and Phylogenetic Interrelationships of the Enigmatic Late Jurassic Shark Protospinax annectans Woodward, 1918 with Comments on the Shark–Ray Sister Group Relationship” by Patrick L. Jambura, Eduardo Villalobos-Segura, Julia Türtscher, Arnaud Begat, Manuel Andreas Staggl, Sebastian Stumpf, René Kindlimann, Stefanie Klug, Frederic Lacombat, Burkhard Pohl, John G. Maisey, Gavin J. P. Naylor and Jürgen Kriwet, 21 February 2023, Diversity.
DOI: 10.3390/d15030311