vertebrates

Cliff Dwelling in Utah Found to Have Unique Decoration: Dinosaur Tracks

Scientists searching for fossils in southern Utah have found that they certainly weren’t the first to prize the traces left behind by dinosaurs.

While on a break from a fossil hunt in Utah’s San Juan County, paleontologists explored a stone structure that had been built under a cliff overhang at least 800 years ago.

While most of the building had been made from cream-colored sandstone found nearby, one piece stood out — the pinkish rock that formed the lintel over the doorway.

It was covered in the fossilized tracks of a theropod dinosaur.

“The slab with the fossilized track appears to have been transported here from another location and then deliberately placed as the lintel in this structure by the builders,” writes paleontologist Joshua Smith, who reported his discovery today with his colleagues at a meeting of geologists in Denver.

“The practice of incorporating vertebrate [track] fossils into cliff-dwelling structures … in the American Southwest is heretofore unknown, and this discovery is the first such documented occurrence.” Read more.

“I miss dinosaurs.”

“Evolution, we’ve talked about this.”

“But I miss them.”

“You turned them into birds, remember? It was the best you could do, given the circumstances.”

“It’s not the same.”

“I know. I’m sorry.”

“Can I at least make these cassowaries 50 feet tall?”

“Come on, you know that size didn’t work out so well before.”

“Six feet, then? And over 100 pounds?”

“Yeah, that sounds better.”

“And can I put weird prehistoric crests on their heads?”

“I don’t see why not.”

“And can they slash people’s throats with their dagger claws?”

“Sure, pal, if that would make you feel better.”

“I think it would. Thanks for understanding.”

“You got it, evolution. Anytime.”

Source: Wikimedia Commons / Bjørn Christian Tørrissen

“So I’m working on a new concept. It’s called ‘parental care.’”

“What does that mean, evolution?”

“It means that instead of just laying her eggs and then leaving them to fend for themselves, like most amphibians do, this caecilian is going to stick around and feed them after they hatch.”

“Oh, that’s nice! What’s she going to do, bring them termites and stuff?”

“What? No. I didn’t even give her arms.”

“Okay, but maybe she could—”

“No, no. What she’s going to do is grow an extra layer of skin that’s super-fatty and nutritious, and then she’s going to sit there while her young tear the skin off her with their tiny, shredding teeth.”

“I… I’m sorry? They’re going to eat their mother’s skin?

“I prefer the term ‘graze on.’”

“That’s horrifying.”

“Like that’s ever stopped me before.”

Source: Wilkinson et al., 2013 / licensed under CC BY 2.5
Meet another species of caecilian in the WTF, Evolution?! book!

npr.org
Talk About An Ancient Mariner! Greenland Shark Is At Least 272 Years Old
This Arctic species can live longer than any other known animal advanced enough to have a backbone, scientists say — maybe more than 500 years. Their muscles might hold clues that could help humans.

The Greenland shark, a massive carnivore that can be more than 16 feet long, hasn’t been studied much, and its life in the cold northern waters remains largely mysterious. Julius Nielsen, at the University of Copenhagen in Denmark, says there had been some hints that Greenland sharks grow very slowly, perhaps less than a centimeter per year. That suggested the huge sharks might be ancient.“We only expected that the sharks might be very old,” says Nielsen.

“But we did not know in advance. And it was, of course, a very big surprise to learn that it was actually the oldest vertebrate animal.”

He and some colleagues obtained 28 female Greenland sharks taken by research vessels as unintended bycatch from 2010 to 2013. The researchers then used radiocarbon dating techniques on the lenses of the sharks’ eyes.

There’s a bit of uncertainty associated with the age estimates, but Nielsen says the most likely age for the oldest shark they found was about 390 years. “It was, with 95 percent certainty, between 272 and 512 years old,” he says. The researchers believe these sharks reach sexual maturity at about the age of 150 years.

5

Clearing and staining, or diaphonization, is a process used by vertebrate biologists when seeking to visualize a particular animal’s skeletal system. Some steps include submerging the specimen in containers of digestive enzymes to render their organs translucent, while other steps involve immersing the animal in alizarin red dye, which adheres to calcium in their bones and stains them red, and alcian blue dye, which reacts with the cartilage of their joints. The results manage to be useful for studying biomechanical function and skeletal morphology, as well as appear stunningly beautiful. 

Learn more of this process by watching our latest episode: Clearing and Staining Fishes

The Greenland shark can live to be 400 years old. Researchers discovered this longevity by carbon dating the sharks’ eyes based on the fallout from nuclear bomb testing in the 1960s, which means there are sharks in the ocean that were born before the United States was a country. Source Source 2

Sharks are over 420,000,000 years old.

That’s older than flowering plants, older than trees, 200,000,000 years older than dinosaurs, almost older than vertebrates or animal life on land, and far, far, far older than anything even remotely resembling a mammal. 

They’ve survived three ice ages and the rise and fall of the great aquatic invertebrates, the primitive reptiles, the dinosaurs, the warm-water whales, and the mammalian megafauna that came just before us.

They’ve survived virtually unchanged since the dawn of vertebrate life, too. If you found a picture of a primitive shark and showed it to someone who knew nothing about marine life, they’d go “oh, yeah, that’s a weird-looking shark”. 

And they are headed for extinction some time in the next century if we continue killing them at this rate. There is still hope, the numbers are lowering more slowly and there are increasing populations in well-managed fisheries, but the four-hundred-and-twenty-million-year-old tops of our food chains are dying out for no other reason than because killing them is profitable. 

Spread the word, everyone. Education is the key to getting shark finning banned, to pushing (or forcing) methods of fishing that reduce bycatch, and to convincing people that sharks are not monsters. 

Developing acorn worm

Acorn worms live deep in the ocean feeding on organic matter from sand and mud on the sea floor. Though simple in appearance, they possess highly specialized organ systems compared to any other worm-like organism including a heart that also functions as a kidney. In this image, a larval acorn worm shows developing musculature and nerves, providing insights into how animals with full spines and brains determine their body structure as embryos. Recent research has revealed that the three signaling centers that control brain development in vertebrates also control the development of the three body regions in acorn worms, showing how evolution has altered the function of these centers to be brain-specific.

Image by Dr. Sabrina Kaul, University of Vienna.