The Artifact: The Theropod Gap

Why do you get deja vu? Why are you attracted to symmetrical faces and why do you listen to songs a bum you out? I'm just the host of a new podcast, deeply human when you cry. It can sometimes look how cute you are attempting to induce Deja Vu, through virtual reality, we all want to know why you do what you do, deeply human, BBC World Service, and American public media co-production with iheartmedia, listen on the iHeartRadio app, on Apple podcasts or wherever you get your podcasts.

Problem of racism is before us threatening our very existence, how are we going to free Humanity from this virus?

I'm even Mexican Dee the host to be anti-racist. New action podcast launching on June, 9th, from iheartmedia the Pushkin Industries, listen to be anti-racist on the iHeartRadio app Apple podcast or wherever you get your podcast.

Welcome to stuff to blow your mind. A production of iHeartRadio.

Hi, my name is Joe McCormick and this is the artifact a short-form series from stuff to blow your mind. Focusing on particular objects, ideas and moments in time,

despite what you might see in some classic picture books, not all species of dinosaurs live together. At the same time, he might have seen an illustration where a tyrannosaurus is opening. Its jaws to clamp down on the neck of a loan stegosaurus, while the stegosaurus raises the end of its Spike tail and defense, but this never happened. We know. It never happened because the Tyrannosaurus lived about 66 million years ago and the stegosaurus genus lived, a hundred and fifty million years ago. The time between them was more than 80 million years, which is actually greater than the time between the extinction of the non-avian dinosaurs and us. If you show a T-Rex fighting a Stegosaurus, you might as well show a group of humans hunting a Triceratop just like us dinosaurs lived. Within particular ecological. Communities groups of organisms that all occupied the same time and place. And when you look at fossils, in terms of it,

Official communities interesting questions. Going to rise this week. I came across a study published in the journal science in February 2021 by a group of paleo ecologists named Kaitlyn Schroeder. S Cathleen Lyons and Felicia A Smith which discussed a potentially mysterious Gap. That emerges when you try to put together a picture of these dinosaur communities, from the fossil record, most of the time. These communities are missing something medium-sized carnivores, this Gap and medium-sized animal seems specific to dinosaurs and carnivorous dinosaurs in particular, rather than something that is generally observed in nature. For example, if you look at the carnivores that live in the African Savanna today you'll find small carnivores like the Mongoose large carnivores like the lion and in between plenty of medium-sized carnivores like the Wild dog, the environment allows niches for meat eaters of all these sizes because each can evolve to specialize

Pray, that's best suited for its body mass, but when it comes to communities of dinosaurs the distribution, often appears to have this hole in the middle, there were giant Predators the ones we know very well, the mega theropods, like, Tyrannosaurus, Rex, the class known as Mega, theropods includes any theropod Predator that grew to over a thousand kilograms. And there were some small Predators as well body masses under 100K, but there was often very little in between these communities. Mostly didn't have predators that were over a hundred kilograms but under a thousand to use a comparison cited in the study itself. Quote, if the modern mammal carnivore, assemblage of the Kruger National Park were similarly structured, there would be no carnivores between the size of an African lion at 190, kg and a bat-eared fox at 4. So what accounts for the dinosaur cap?

When there's an apparent Gap in the fossil record, there's always a possibility that what paleontologists are seeing is merely a bias in the fossilization process. Most of the animals that live and die, never become fossils. Fossilization is a special process that only takes place under unique conditions. For example, when the bones are rapidly buried after the animal's death, this is much more likely to happen in a wet environment like a sea floor, which is why we have far more fossils of prehistoric marine organisms than we do have land animals. And when we do you have the fossils of a land animal, it's often because their bones somehow fell into a water source, so we're covered by a flood, but Schroeder at all in their paper argue for a different explanation, after the exam and 43 communities of dinosaurs across a hundred and thirty-six million years. They concluded that the mezzo carnivore. Gap is real and the explanation has to do with how dinosaurs

Reproduced and grew the largest theropod Predators were gigantic. Once they reach full size and adult Tyrannosaurus, Rex, probably grew to more than 12 meters in length and wait somewhere between 4000 and 7000 kg there often compared to the size of large vehicles. But there's a fact that limits, how big the offspring of even. The biggest dinosaurs could be when they entered the environment. Dinosaurs are oviparous they hatch from eggs, mammals, on the other hand are viviparous giving birth to live young and the newborns could be pretty stout African elephant, calves. Are sometimes already over a hundred kilograms of the time. They're born. This gives those calves a leg up on Survival but it also comes with biological costs. Mammals usually have fewer Offspring, The November of species and they have to invest more resources into each one. An African elephant mother is pregnant with each calf for almost 2 years and even after the calf

Warren, it's been several more years nursing but while egg-laying species don't have these problems. They're also drawbacks to egg-based reproduction. For example, there are harsh physical constraints, on the size of eggs. The shell of an egg has to be thin enough to allow the permeation of gas. So oxygen can get inside and reach the developing embryo, and the shell also has to be thin enough to allow the hatchling to break out once it reaches maturity. But as eggs increase in size than shells, become less and less tenable, a huge egg with a wafer like shell would break too easily. As a result, even gigantic dinosaurs would have to lay a pretty small eggs Shredder it all right? That oviparity men, even the largest dinosaur species were limited to about 15 kg which is roughly about 33 lb. At the time that they hatched, no matter how big the adult, the new hatchlings were never going to be any bigger than your average Welsh Corgi.

Freshly hatched Tyrannosaurus, Rex was probably about the size of a house cat. So these Mega theropods started. Very small group enormous, in adulthood and had a lot of eating and growing to do along the way and there were lots of them. Ultimately, this is the explanation offered by the authors of the 2021 paper, for the mezzo carnivore Gap. The Gap was filled by growing Mega theropods. In other words, these communities did have their own medium sized carnivores, but they weren't separate species. They were the rampaging juveniles of giant mega theropod creditors. The young functioned in the community almost as a species of their own and buy functioning like different species in their juvenile phases. Mega theropods limited species diversity. There's just less room in the environment for a predator that reaches 300 kg as an adult. If there are lots of 300kg t-rex teenagers running around competing for the same

Tune into new addition to the artifact every Wednesday hosted by either Robert or myself. As always, you can email us at contact at stuff to blow your mind. Calm.

Stuff to blow your mind is production of iHeartRadio from war podcast from iHeartRadio for the iHeartRadio app Apple podcast or wherever you listen to your favorite shows. Davis on the plane guy podcast. As a two-time All-Star, I know, not all men are created equal. Some are born with true god-given Talent. I'm Baron Davis. And on my new iheartpodcast playing God, we get to dive deep into the art strategy, the science, the mathematics around. What it means to be a point guard on the point guard, podcast on the iHeartRadio app Apple podcast or wherever you download your podcast.

Hi. This is Rex Chapman. You might know me for my former life as an NBA player or for my spectacular Fall From Grace or maybe just follow me on Twitter. Now I'm hosting a new podcast called charges with Rex Chapman, each episode centers around an interview with a famous athlete or Entertainer who ran afoul of the law will relive, their rise to fame as well as their Fall From Grace and hear their side of the events that changed our lives forever. And really want to let people know with the people that we're going to talk to that. You never as bad as your worst moment. As long as you learn from it, you know, I'm planning on having guys on the guys, I know guys, I don't know who run afoul of call it charges, cuz you've been charged with something. It was an ugly time as a tough time in your life and that moment when it happened to you is really painful to talk about. But I think it's cathartic and I think people will get a lot out of it. Listen to charges with Rex Chapman on the iHeart.

Video app Apple podcasts or wherever you listen to podcast.