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Paleontologists think they've solved part of the mystery of the Cleveland-Lloyd Dinosaur Quarry, a dense bed of Jurassic dinosaur fossils. Also, electron microscope images reveal new, mucus-drenched info about the tubelip wrasse.

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The Jurassic period lasted from about 200 to 145 million years ago. And toward the end of it, a bunch of dinosaurs somehow died at what’s now the Cleveland-Lloyd Dinosaur Quarry in Utah, creating the densest known bed of Jurassic dinosaur fossils.

Over 60% of the fossils found in this death trap have been Allosaurus, a top predator of the Jurassic. Long before T. rex, Allosaurus was the king of scary bitey things. Ever since the quarry was discovered in 1927, scientists have been scratching their heads as to why a bunch of reptiles, especially so many predators, would just march in there and die.

In a study published this week, though, a team of researchers have created a clearer picture of the environment at the site using two main lines of evidence. They used x-ray techniques to study the geochemistry of rock formation, and looked at the wear pattern on tiny fragments of bone that paleontologists might typically gloss over, because they’re too small and busted up to help with species identification. 148 million years ago, these researchers say, the Cleveland-Lloyd site was a seasonal pond -- wet for part of the year and dry the rest. Dinosaur corpses would have been washed there by the floods that filled the pond during the wet season. In other words, the to-be-fossils were already dead when they arrived.

The rotting corpses would have made the pond incredibly nasty, so much that scavengers stayed away and not much else lived there. The rocks in the site contain heavy metals like copper and lead. Previously, scientists had used this evidence to suggest that the water hole was poisonous.

But, based on this geochemical analysis, the current researchers think it’s more likely that the metals came from the dinosaurs’ already-decaying bodies. As the pond dried out, bones near the surface weathered and cracked, producing the fragments that these researchers studied. While bones buried further down in the muck were preserved intact.

And as the floods came again, more corpses washed in. The team figures all this took place over a decade or two, creating the boneyard we’re excavating today.

But why so many Allosaurus? The fact that there were a lot of them doesn’t necessarily tell us anything about their behavior. Non-social animals can be driven together for lots of reasons, like water. The only egg ever recovered from the quarry seems to belong to an Allosaurus, so maybe they used the Cleveland-Lloyd site to breed. But there’s not enough evidence to say that for sure.

So while this new study reveals the pretty gross nature of the Cleveland-Lloyd graveyard, scientists still have some pieces of the puzzle to figure out.

Like Allosaurus, the tubelip wrasse is a predator. But this tiny fish feeds on coral, and it’s developed some weird strategies for slurping up its prey. In a study published this week in the journal Current Biology, a team of researchers got up close and personal with its lips -- and they have the freaky photos to prove it. Lots of fish live in coral reefs, but relatively few actually eat the coral.

Coral isn’t the easiest snack. For one thing, its skeleton is basically made of rock. Plus, corals are related to anemones and jellyfish, and the fleshy polyps have nasty stinging cells called, which resemble tiny harpoons that spear prey or potential attackers and can inject chemicals.

Different coral-eating fish have different ways of getting around these defenses. Parrotfish, for example, favor the brute force approach. They just bite the stony coral skeleton right off with their strong beaks, grind it up, and poop it out as fine sand.

Researchers studying the tubelip wrasse found a far more sophisticated feeding strategy -- closer to a kiss… of death. Scientists thought the tubelip wrasse had plain, smooth lips. But the team took up-close electron micrographs that blew that assumption right out of the water.

It turns out the lips are big, fleshy, and have a bunch of deep folds. These folds are jam-packed with mucus-producing cells, and increase the lip surface area for maximum slime production. The mucus could work like the coating on clownfish that helps them fend off the nematocysts of anemones, which might be a slimy physical barrier or have a chemical component to stop the cells from stinging in the first place.

Although they don’t know the exact strategy, the researchers believe the tube lip wrasse’s mucus works a similar way to protect their mouths when they go in for a slurp. And the mucus has another function: It helps the fish’s lips seal shut around the lumpy coral, which helps it suck in one particularly tasty part: the polyps’ own mucus, plus some flesh chunks.

These creepy grooved lips are unlike anything previously known to science. So who knows what else we might find by looking more closely at animals we think we already understand.

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