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The Field Museum
The Field Museum

Scientists Find New Method to ID the Sex of a Dinosaur

The Field Museum
The Field Museum

How do you tell a male dinosaur from a (possibly) female dinosaur such as Sue, The Field Museum's famous Tyrannosaurus rex? (Sue may not be female—more on that in a minute.) 

For decades, paleontologists have sought more accurate ways of identifying the sex of dinosaurs. Characteristics like size and, in some species, fancy ornamentation—horns and crests, for instance—can be sex indicators, but not always beyond the shadow of a doubt. In fact, Sue was so named in honor of Sue Hendrickson, the paleontologist who discovered the dinosaur's remarkably intact remains—not because we know for sure she was female. The Field Museum says the T. rex's sex is actually unknown. 

Our ability to ID the sex of dinosaurs like Sue should improve in the future, thanks to the 68-million-year-old femur of a pregnant Tyrannosaurus rex. Using this bone, researchers have found a new molecular tool to more reliably determine from fossil remains whether a dinosaur was male or female. The team recently published their findings in Scientific Reports.

The key lies in the medullary bone, a reproductive tissue only found today in female birds around the time of egg laying that is chemically distinct from other types of bone. Meat-eating theropod dinosaurs like T. rex, which are related to modern birds, also laid eggs, raising the possibility that pregnant female theropods may have produced medullary bone during their reproductive cycle.

“We know that there’s sexual signaling among almost all organisms on the planet that reproduce sexually,” lead author Mary Schweitzer, a paleontologist at North Carolina State University and the North Carolina Museum of Natural Sciences, told mental_floss. “You’ve got to have a way to tell males and females, so it’s not surprising that dinosaurs would have this.”

About a decade ago, Schweitzer found what she believed was medullary bone in a T. rex fossil that had been discovered in Montana. But she needed to rule out other possibilities, such as symptoms of diseases that can mimic the appearance of medullary bone under a microscope.

A chemical analysis was the only way to be sure. Schweitzer and her team knew that medullary bone contains a substance called keratan sulfate that is not present in other kinds of bone. If they identified keratan sulfate in the Montana fossil sample, it would confirm the presence of medullary bone. 

But could evidence of keratan sulfate molecules persist in a fossil for tens of millions of years? As it turned out, yes. 

Schweitzer and her colleagues then compared the tissue found in the T. rex to medullary tissue in ostrich and chicken bones. They used a chemical stain that turns a vivid blue when it reacts with the keratan sulfate molecules found in medullary bone. Both the bird samples and the T. rex sample reacted similarly, indicating the presence of medullary bone.

Schweitzer said the research points to new ways that molecular biology might be used to resolve some of the conflicts and ambiguities in the fossil record. The hope now is that this chemical method can be extended to help unravel other mysteries, like determining dinosaur age and studying population structure.

“It’s one more piece of evidence that original molecules persist in fossils, and we can begin to use this molecular information to ask questions that we previously thought we could only ask of living organisms,” said Schweitzer. 

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NOAA, Wikimedia Commons // Public Domain
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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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