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Ever wonder what a dinosaur might have looked like? Well, we might have an answer for you and the result is hidden in plain sight.

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Dino shading

Speedy snail insulin
[SciShow intro plays]

Hank: At some point, we’ve all wondered what dinosaurs actually looked like – especially their color patterns. Were they solid? Striped? Dappled? Covered in polka-dots? Many people thought we could never know for sure, but research published this week revealed what might be the most accurate dinosaur reconstruction ever made... And it’s particularly well-camouflaged for life in forests.

The specimen was an extremely well-preserved fossil of Psittacosaurus, with pigment-containing structures called melanosomes that gave clues to the dinosaur’s coloration. And the researchers – led by Jakob Vinther from the University of Bristol – wanted to bring it to life.

Though not like in a Jurassic Park kind of way. They recruited a paleoartist to construct a life-size color model of Psittacosaurus, using careful measurements of the fossilized body and pattern of melanocytes. Overall, the dinosaur was darker on top and paler underneath – a classic case of countershading, or 3D camouflage.

See, the way light falls on objects affects how we know what we’re looking at. When they’re lit from above, 3D objects look palest on top, since more light bounces off and into our eyes. Meanwhile, the underside has darker shadows.

Many animals, including humans, are instinctively pretty good at noticing 3D things – like other animals – based on the way light bounces off them. But when the sun’s shining, an animal with countershading – darker on top and lighter underneath – looks more evenly colored, and doesn’t stand out as much from its background. So, 3D camouflage has evolved in lots of animals to stay safe from hungry predators, but the exact pattern of countershading depends on their habitat.

Animals living in bright, open areas like a savannah tend to have abrupt countershading, for example, while the diffuse lighting of forests favor a gradation. Knowing this, the researchers wanted to use their Psittacosaurus model to understand where it might have lived. To figure it out, they took pictures of a solid gray copy of the model in different outdoor environments, to see how light would have fallen on the dinosaur’s body.

Then, they used computers to compare these photographs with the observed countershading from the fossil, to see which environment would’ve helped the dinosaur blend into the background. What they found is that Psittacosaurus was most likely adapted for forest life. Just like forest-dwellers today, the countershading pattern produced by the dinosaur’s melanocytes was probably subtle, switching from dark to light fairly low on its body.

The fact countershading evolved at all means some predatory dinosaurs may have had vision similar to current animals that hunt. And the researchers hope that more well-preserved fossils will help them paint a more complete picture of how dinosaurs looked, and how they saw the world. Now, as far as predatory animals go, snails don’t seem cut out for hunting – they’re notoriously slow.

But some species, like the ocean-dwelling geographic cone snail, have weaponized a fast-acting form of insulin to stun fish and nab a meal. Insulin is a peptide hormone that lowers blood glucose levels. In humans, it’s normally released if your blood sugar gets too high – like after a big meal.

As it turns out, this specialized insulin could help treat Type I diabetes someday, and it’s all thanks to some fancy folding in the protein structure. When the geographic cone snail is on the hunt, it pumps a venom cocktail, including a kind of insulin, into the water where fish are swimming around, causing their blood sugar levels to crash. And low blood sugar can be really dangerous, because animal cells need a steady supply of glucose to function.

The insulin overdose sends the fish into a coma-like state called hypoglycemic shock, giving the snail plenty of time to devour it. This fast-acting killer hormone was only described last year, and the researchers involved wondered whether it could help human medicine. See, people with Type I diabetes can’t make their own insulin, so they have to inject some if their blood glucose gets too high.

Human insulin molecules are stored in clusters of six, thanks to a sticky patch at one end of the peptide – a hydrophobic region that also helps insulin bind to receptors and tell cells to take up glucose. Normally, it takes around 15 minutes for the insulin proteins to separate and start doing their thing. That’s usually fine, but not good in an emergency.

But the researchers estimate that this snail-made insulin could get to work in just 5 minutes. They studied the sequence of amino acids in the snail-made insulin, and noticed the sticky patch was completely missing. So these proteins don’t form clusters.

But if that hydrophobic region helps human insulin bind to our cell receptors, how would this insulin manage it? Using X-ray crystallography and molecular modelling, the scientists found that part of the snail-made insulin molecule folds and rotates in specific ways to create a new sticky patch that mimics the human insulin region. But this shift only happened when the snail-made insulin bound to the human receptor, which is why this insulin doesn’t cluster up. So despite the molecule’s deadly origins, the scientists hope that, with more research and experiments, this cone snail insulin could inspire emergency treatments that save lives.

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