Cosmic Science

Dinosaur super-necks, flipped fossils and other paleo bits

Paleontologists find the darndest things — including evidence for the longest-known sauropod neck, and fossils that literally turn their assumptions upside down. Check out these fresh developments from the fossil record:

Dinosaur’s neck sets a record

Researchers say a Jurassic sauropod whose 162 million-year-old remains were dug up in China had a 50-foot-long (15-meter-long) neck. That would be longer than the neck of any other known sauropod species. And that’s saying a lot: Sauropods were plant-eating dinosaurs whose long necks were eminently suited for foraging.

If the researchers are right, the neck of a dinosaur known as Mamenchisaurus sinocanadorum was about 10 feet longer than a typical school bus, or more than six times as long as the neck of a giraffe, which is the current record-holder for living animals.

The researchers based their conclusion on detailed studies of a handful of specimens from the fossilized creature’s neck and skull — fragmentary specimens that were dug up in 1987 and identified as representing a previously unknown species in 1993. Their morphological analysis was fed into a model for comparison with more complete skeletons from similar sauropod species. The results were published online today by the Journal of Systematic Paleontology.

“All sauropods were big, but jaw-droppingly long necks didn’t evolve just once,” Stony Brook University’s Andrew Moore, the study’s lead author, said in a news release. “Mamenchisaurids are important because they pushed the limits on how long a neck can be, and were the first lineage of sauropods to do so. With a 15-meter-long neck, it looks like Mamenchisaurus sinocanadorum might be a record-holder – at least until something longer is discovered.”

Moore and his colleagues used X-ray scans to determine that the dinosaur’s neck bones would have been filled with air, like the bones of a stork, to reduce their weight.

“Biomechanical studies of the mamenchisaurid neck suggest that it was elevated at only a relatively shallow angle above the horizontal (20-30 degrees),” said study co-author Paul Upchurch, a paleobiologist at University College London. “However, even at this relatively shallow angle, the extreme length of the neck would still mean that the animal’s head could reach heights of around 7.5 to 10 meters [25 to 33 feet] above ground level, facilitating feeding on tree foliage.”

Paleontologists flip the fossil script

Illustration: Ancient anemones and jellyfish buried by sediment
A cluster of ancient sea anemonies is inundated by an underwater sediment avalanche while ancient jellyfish swim above. (Illustration by Julius Csotonyi for University of Illinois at Chicago)

There are billions of sea anemones on the bottom of Earth’s modern-day oceans — but for decades, paleontologists had thought that ancient sea anemones were among the rarest of specimens because their squishy bodies lacked easily fossilized hard parts.

Now a research team reports that plenty of sea anemone fossils have been hiding in plain sight. In a study published by Papers in Paleontology, the team says fossils that had long been interpreted as ancient jellyfish were actually anemones turned upside down.

“Anemones are basically flipped jellyfish,” lead author Roy Plotnick, professor emeritus of earth and environmental sciences at the University of Illinois at Chicago, said in a news release. “This study demonstrates how a simple shift of a mental image can lead to new ideas and interpretations.”

The flipped-out specimens come from the 310 million-year-old Mazon Creek fossil deposits in northern Illinois. An ancient delta at the site allowed for the preservation of soft-bodied organisms because the anemones and other animals were rapidly buried in muddy sediments.

“These fossils are better preserved than Twinkies after an apocalypse. In part that’s because many of them burrowed into the seafloor as they were being buried by a stormy avalanche of mud,” said study co-author James Hagadorn, an expert on unusual fossil preservation at the Denver Museum of Nature and Science.

Fossil collectors have long known about the “blobs” at Mazon Creek. In 1979, geologist Merrill Foster identified the blobs as a type of jellyfish with an unusual “curtain” that hung down from the creature’s umbrella-shaped “bell.” But Plotnick and his colleagues came up with a different description after examining thousands of museum specimens.

“It quickly became obvious that not only wasn’t it a jellyfish, but turned upside down it was clearly an anemone, probably one that burrowed into the seafloor. The ‘bell’ was actually an expanded muscular foot used to wiggle the anemone into the seafloor,” Plotnick said.

The “curtain” was the barrel-shaped body of the anemone.

Being able to survey a wide variety of jellyfish fossils … er, anemone fossils … was key to cracking the case. “Although most of these fossils are preserved as decomposing blobs that look like a piece of used gum on the sidewalk, some specimens are so superbly preserved that we can even see the muscles that the anemones used to bend and contract their bodies,” said study co-author Graham Young, an expert on fossil jellyfish at the Manitoba Museum.

The granddaddy of ichthyosaurs

Illustration: Ichthyosaur and other sea creatures
An artist’s conceptions show an ichthyosaur and the 250 million-year-old ecosystem found on Spitsbergen. (Illustration by Esther van Hulsen)

Swedish and Norwegian paleontologists say they’ve found the remains of the earliest known ichthyosaur, or “fish-lizard,” on the remote Arctic island of Spitsbergen. The discovery of the 250 million-year-old fossils could cause the tale of ichthyosaurian evolution to be rewritten.

Scientists had previously thought ichthyosaurs arose well after the Permian mass extinction that occurred a little more than 250 million years ago, when land-based reptiles evolved to take advantage of marine predator niches that were left vacant by “the Great Dying.”

But if the newly discovered fossils have been dated correctly, that suggests ichthyosaurs must have been around before the Permian extinction took place.

“The discovery of the oldest ichthyosaur rewrites the popular vision of Age of Dinosaurs as the emergence timeframe of major reptile lineages,” Benjamin Kear, a researcher at Uppsala University’s Museum of Evolution and the lead author of a study published by Current Biology, said in a news release. “It now seems that at least some groups predated this landmark interval, with fossils of their most ancient ancestors still awaiting discovery in even older rocks on Spitsbergen and elsewhere in the world.”

How dinosaurs used their crazy claws

Illustration: Dinosaur claw grabbing a tree
An artist’s conception shows the claws of a therizinosaur hooking and pulling a tree. (Illustration by Shuyang Zhou)

Dinosaur claws weren’t just weapons. They could also serve as tools for digging up bugs, or as ways for prehistoric reptiles to show off.

That’s the bottom line for a study conducted by researchers from the University of Bristol in Britain and the Institute of Vertebrate Paleontology and Paleoanthropology in China.

The team focused on two groups of theropod dinosaurs known as alvarezsaurs and therizinosaurs. Those distant cousins of T. rex had bizarre claws whose function had been a mystery up to now. Now researchers surmise that alvarezsaurs used their rock-pick-like claws for digging, while their close relatives, the giant therizinosaurs, used their overdeveloped, 3-foot-long claws for display.

The study in Communications Biology was led by Zichuan Qin, a researcher associated with the University of Bristol as well as IVPP. He developed a computational approach in biomechanics to identify functions based on detailed comparison with living animals. First, the claws were modeled in three dimensions from X-ray scans, then modeled for stress and strain using engineering methods, and finally matched to functions of pulling, piercing and digging by comparison with modern animals whose claw functions are known.

Alvarezsaurs, which were about the size of modern-day chickens, are thought to have eaten ants and termites — and their claws would have been well-suited for digging in the dirt.

But the story was apparently different for therinosaurs.

“Therizinosaurus is famous for its sickle-like claws, each as long as a samurai sword: Edward Scissorhands on speed. We all saw Therizinosaurus in ‘Jurassic World’ hitting deer and killing the giant predator Giganotosaurus,” study co-author Chun-Chi Liao, an expert on therizinosaurs from IVPP, said in a news release. “However, this is unlikely. These long, narrow claws were too weak for combat. Our engineering simulation shows that these claws could not withstand much stress.”

Instead, the claws “must have evolved under sexual selection to be used in display,” Chun-Chi Liao said. “The adult Therinosaurus, I guess, could wave the claws at a competitor and effectively say, ‘Look at me, back off,’ or wave them around in some way like a peacock can use its tail in display to attract females for mating.”

By Alan Boyle

Mastermind of Cosmic Log, contributor to GeekWire and Universe Today, author of "The Case for Pluto: How a Little Planet Made a Big Difference," past president of the Council for the Advancement of Science Writing.

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