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New fossils reveal first known swimming dinosaur
Non-avian dinosaurs were thought terrestrially bound, but newly unearthed fossils suggest they conquered prehistoric waters, too.
Despite being extinct for 65 million years, dinosaurs continue to evolve in our imaginations. Over the past two hundred years of research, these once terrible lizards have added a panoply of new adaptations, from brightly colored feathers to a syrinx more appropriate for mate-attracting honks than movie-monster roars.
Despite these many changes, one taxonomic rule seemed steadfast: Non-avian dinosaurs lived terrestrial lives. If Mesozoic reptiles flew, like Pterodactylus and Pteranodon, then they were not dinosaurs. If they swam, like Ichthyosaurus or Plesiosaurs, then they were not dinosaurs.
But new Spinosaurus aegyptiacus fossils excavated in the Kem Kem region of the Moroccan Sahara may have rewritten those rules and our understanding of the Mesozoic world.
Unearthing a mystery in the desert
Stromer's holotype of his original Spinosaurus specimen.
Spinosaurus was a Cretaceous period therapod, a clade of dinosaurs that include Velociraptor, Dilophosaurus, Giganotosaurus, and of course, Tyrannosaurus rex. At nearly 40-feet long and weighing an estimated 6 tons, Spinosaurus is one of the largest predatory dinosaurs ever discovered, yet many of its characteristics have confounded paleontologists for decades.
The first Spinosaurus fossils were discovered in 1912 by Ernst Freiherr Stromer von Reichenbach, a paleontologist and German aristocrat. Stromer's specimen mainly consisted of jaw fragments and neural spines, but that proved enough to convince him of his discovery's peculiarities.
Unlike T. rex's stout, powerful jaw, Spinosaurus had a slender yard-long snout more akin to a crocodile's. Its conical teeth were ill-suited to shearing and tearing like other therapods' serrated teeth; they were a better match for snapping the fish out of water. Then there was that characteristic spine sail.
Unfortunately, Spinosaurus would remain elusive to Stromer as his original specimen was destroyed in the Allied bombing raids on Munich. Over the decades, however, paleontologists would keep trying to solve the puzzle of Stromer's weird dinosaur.
A digital resurrection
An illustration of a Spinosaurus skeleton with its thinner, more traditionally therapod-like tail.
And Spinosaurus kept getting weirder. In addition to the back-sail and elongated jaw, further fossil discoveries elucidated a dinosaur that was incredibly front-heavy with dense bones and short back legs not tailored for running.
"I tried to see all the bones, the muscles, the connective tissue, everything," Nizar Ibrahim, a paleontologist at the University of Detroit Mercy, told National Geographic. "Sometimes it was there for an instant, then it vanished, like a mirage. My brain couldn't quite compute all that complexity."
As reported in National Geographic, Ibrahim teamed up with Simone Magnuco at the Milan Museum and University of Chicago fossil preparator Tyler Keilor in 2014 to digitally resurrect Spinosaurus.
The team used a CT scanner to reconstruct Spinosaurus bones within a computer, including some unearthed by Ibrahim in Morocco. They rounded out their skeleton by assembling missing bones from images of museum specimens, Stromer's original photographs and sketches, and those from other therapod specimens.
When they saw Spinosaurus walk across its digital landscape, they realized the animal was better attuned for an amphibious lifestyle than a terrestrial one. It had nostrils at the tip of its snout. Its bones were dense like aquatic mammals, and its hind legs would not have been such a hindrance if submerged in buoyant hunting grounds.
Their hypothesis also fits with what we know about Spinosaurus's habitat. Today, the Sahara is one of the driest places on Earth, but in the Cretaceous period, vast waterways covered the land and sported giant fish to outsize the most unbelievable of fish stories. (Seriously though, they were this big.)
A study of lost tails
But something was missing: a means of propulsion. How did a giant like Spinosaurus catch slick and quick prey while paddling like a duck on two stumpy hind legs? It didn't add up.
"The big thing we were missing was a propulsive structure because you can't really be an aquatic predator unless you have some way to catch prey in the water and move through the water," Ibrahim told Nature. "That's what we now found."
Between 2015 and 2019, on a grant from the National Geographic Society, Ibrahim and his team traveled to the Kem Kem region of the Moroccan Sahara to unearth further Spinosaurus fossils. During their dig, they discovered Spinosaurus tail vertebrae that were "characterized by extremely long spines."
Ibrahim's previous reconstruction of Spinosaurus featured a thin tail borrowed from other therapods. But such a tail would make traveling through the water unwieldy—think paddling a canoe with a walking stick. The new vertebrae revealed a fin-like tail, similar in appearance to a newt's, and could more easily propel the dinosaur through the water.
To test his hypothesis, Ibrahim's colleagues at Harvard crafted plastic models of the Spinosaurus tail. They attached it to a robot system that mimics swimming and measured its thrust and efficiency. They then compared the Spinosaurus tail's performance against two other therapod tails and extant aquatic animals.
Spinosaurus's results were consistent with the aquatic animals and superior to the terrestrial therapods. Ibrahim and his team published their results in Nature.
"This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm," Ibrahim said in a release. "This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water."
But as is the case in science, not everyone is yet convinced.
Donald M. Henderson, the curator of dinosaurs at the Royal Tyrrell Museum, believes Spinosaurus likely lived at the water's edge, scooping up fish as they swam by. As he told the New York Times, he does not believe Spinosaurus would be a powerful swimmer.
"My first thing is, they haven't actually demonstrated that this tail could produce enough force to propel a six-and-a-half-ton body through the water," Henderson said. He added that the researchers had yet to provide that Spinosaurus had enough muscle power to move such a tail or compensate for the drag of its sail.
Dinosaurs are alive! Here’s how we know, and why it matters
As new fossils are found and new ideas to test emerge, we'll see if Henderson's concerns capsize the aquatic hypothesis or not.
Even if Spinosaurus is thrown out of the pool, that doesn't mean dinosaurs will forever remain grounded. As reported by the New York Times, a dinosaur fossil called Halszkaraptor escuilliei has features that suggest a partial aquatic lifestyle. These include "a neck like a swan, a snout like a goose, and forelimbs like flippers," but the specimen is so unusual that its authenticity remains a matter of debate.
And what is revealed in these debates will change our understanding of dinosaurs—both those that are gone and those that are still with us.
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A man's skeleton, found facedown with his hands bound, was unearthed near an ancient ceremonial circle during a high speed rail excavation project.
- A skeleton representing a man who was tossed face down into a ditch nearly 2,500 years ago with his hands bound in front of his hips was dug up during an excavation outside of London.
- The discovery was made during a high speed rail project that has been a bonanza for archaeology, as the area is home to more than 60 ancient sites along the planned route.
- An ornate grave of a high status individual from the Roman period and an ancient ceremonial circle were also discovered during the excavations.
Foul play?<p>A skeleton representing a man who was tossed face down into a ditch nearly 2,500 years ago with his hands bound in front of his hips was dug up during a high speed rail excavation.</p><p>The positioning of the remains have led archaeologists to suspect that the man may have been a victim of an ancient murder or execution. Though any bindings have since decomposed, his hands were positioned together and pinned under his pelvis. There was also no sign of a grave or coffin. </p><p>"He seems to have had his hands tied, and he was face-down in the bottom of the ditch," <a href="https://www.livescience.com/iron-age-murder-victim-england.html" target="_blank">said archaeologist Rachel Wood</a>, who led the excavation. "There are not many ways that you end up that way."</p><p>Currently, archaeologists are examining the skeleton to uncover more information about the circumstances of the man's death. Fragments of pottery found in the ditch may offer some clues as to exactly when the man died. </p><p>"If he was struck across the head with a heavy object, you could find a mark of that on the back of the skull," Wood said to <a href="https://www.livescience.com/iron-age-murder-victim-england.html" target="_blank">Live Science</a>. "If he was stabbed, you could find blade marks on the ribs. So we're hoping to find something like that, to tell us how he died."</p>
Other discoveries at Wellwick Farm<p>The grim discovery was made at Wellwick Farm near Wendover. That is about 15 miles north-west of the outskirts of London, where <a href="https://www.hs2.org.uk/building-hs2/hs2-green-corridor/" target="_blank">a tunnel</a> is going to be built as part of a HS2 high-speed rail project due to open between London and several northern cities sometime after 2028. The infrastructure project has been something of a bonanza for archaeology as the area is home to more than 60 ancient sites along the planned route that are now being excavated before construction begins. </p><p>The farm sits less than a mile away from the ancient highway <a href="http://web.stanford.edu/group/texttechnologies/cgi-bin/stanfordnottingham/places/?icknield" target="_blank">Icknield Way</a> that runs along the tops of the Chiltern Hills. The route (now mostly trails) has been used since prehistoric times. Evidence at Wellwick Farm indicates that from the Neolithic to the Medieval eras, humans have occupied the region for more than 4,000 years, making it a rich area for archaeological finds. </p><p>Wood and her colleagues found some evidence of an ancient village occupied from the late Bronze Age (more than 3,000 years ago) until the Roman Empire's invasion of southern England about 2,000 years ago. At the site were the remains of animal pens, pits for disposing food, and a roundhouse — a standard British dwelling during the Bronze Age constructed with a circular plan made of stone or wood topped with a conical thatched roof.</p>
Ceremonial burial site<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzMTk0Ni9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NDgwNTIyMX0.I49n1-j8WVhKjIZS_wVWZissnk3W1583yYXB7qaGtN8/img.jpg?width=1245&coordinates=0%2C82%2C0%2C83&height=700" id="44da7" class="rm-shortcode" data-rm-shortcode-id="46cfc8ca1c64fc404b32014542221275" data-rm-shortcode-name="rebelmouse-image" alt="top down view of coffin" data-width="1245" data-height="700" />
A high status burial in a lead-lined coffin dating back to Roman times.
Photo Credit: HS2<p>While these ancient people moved away from Wellwick Farm before the Romans invaded, a large portion of the area was still used for ritual burials for high-status members of society, Wood told Live Science. The ceremonial burial site included a circular ditch (about 60 feet across) at the center, and was a bit of a distance away from the ditch where the (suspected) murder victim was uncovered. Additionally, archaeologists found an ornately detailed grave near the sacred burial site that dates back to the Roman period, hundreds of years later when the original Bronze Age burial site would have been overgrown.</p><p>The newer grave from the Roman period encapsulated an adult skeleton contained in a lead-lined coffin. It's likely that the outer coffin had been made of wood that rotted away. Since it was clearly an ornate burial, the occupant of the grave was probably a person of high status who could afford such a lavish burial. However, according to Wood, no treasures or tokens had been discovered. </p>
Sacred timber circle<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUzMTk0Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MDAwOTQ4Mn0.eVJAUcD0uBUkVMFuMOPSgH8EssGkfLf_MjwUv0zGCI8/img.jpg?width=1245&coordinates=0%2C149%2C0%2C149&height=700" id="9de6a" class="rm-shortcode" data-rm-shortcode-id="ee66520d470b26f5c055eaef0b95ec06" data-rm-shortcode-name="rebelmouse-image" alt="An aerial view of the sacred circular monument." data-width="1245" data-height="700" />
An aerial view of the sacred circular monument.
Photo Credit: HS2<p>One of the most compelling archaeological discoveries at Wellwick Farm are the indications of a huge ceremonial circle once circumscribed by timber posts lying south of the Bronze Age burial site. Though the wooden posts have rotted away, signs of the post holes remain. It's thought to date from the Neolithic period to 5,000 years ago, according to Wood.</p><p>This circle would have had a diameter stretching 210 feet across and consisted of two rings of hundreds of posts. There would have been an entry gap to the south-west. Five posts in the very center of the circle aligned with that same gap, which, according to Wood, appeared to have been in the direction of the rising sun on the day of the midwinter solstice. </p><p>Similar Neolithic timber circles have been discovered around Great Britain, such as one near <a href="https://bigthink.com/culture-religion/stonehenge-sarsens" target="_blank">Stonehenge</a> that is considered to date back to around the same time. </p>
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Research reveals a new evolutionary feature that separates humans from other primates.
- Researchers find a new feature of human evolution.
- Humans have evolved to use less water per day than other primates.
- The nose is one of the factors that allows humans to be water efficient.
A model of water turnover for humans and chimpanzees who have similar fat free mass and body water pools.
Credit: Current Biology
Being skeptical isn't just about being contrarian. It's about asking the right questions of ourselves and others to gain understanding.