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Nevilledog

(51,200 posts) Wed Oct 21, 2020, 06:51 PM Oct 2020

We Finally Know What a Dinosaur's Butthole Looks Like

We Finally Know What a Dinosaur’s Butthole Looks Like

https://slate.com/technology/2020/10/dinosaur-butt-fossil-discovery-cloaca.html

For the entirety of my career as a journalist covering paleontology, I’ve been wanting to know: What does a dinosaur’s butthole look like? When I wrote My Beloved Brontosaurus, a book about dinosaur biology, the chapter on reproduction required a lot of time imagining the nature of a Jurassic behind; one had yet to be found preserved. Even dinosaur models and sculptures often demur on the point of the dino butt, leaving the terrible lizards with terrible constipation.

Now I finally have a clearer view, thanks to a fossil of a horned dinosaur called Psittacosaurus, described in a paper online earlier this month. These dinosaurs, which lived over 100 million years ago in what’s now northeastern China, were odd little creatures. While belonging to the same branch of the dinosaur family tree as Triceratops, these Labrador retriever–size dinos walked around on two legs and had beaks like those of parrots, cheeks that were each adorned with a flared horn, and, jutting from the tail, a spray of featherlike bristles. Now we also know that they had buttholes like those of crocodiles.

It’s rare to get a look at something soft and fleshy on a dinosaur. We know most of what we know about Psittacosaurus the same way that we know things about most dinosaurs: from their bones. Durable skeletal parts are much more likely than skin and organs to survive the fossilization process, which involves burial and at least partial replacement of the original tissues. Most of the time, after a dinosaur dies, all the soft stuff just decays. But every now and then paleontologists find dinosaur “mummies” that preserve remnants of the soft bits either as impressions or geologically modified pieces of the original flesh. There’s no one way to make an exquisitely preserved dinosaur: Sometimes it happens when a dinosaur is quickly buried in ash; others dry out in the open for a while. For whatever reason, experts have uncovered several Psittacosaurus with preserved soft tissues. The fossilization in some of these specimens is so refined that we even know what colors these dinosaurs were, brown on top and lighter along the belly. The new fossil is one of the more detailed ones. It includes patches of skin and scales as well as the ornamental bristles on the tail. The most remarkable part is a patch of tissue between the hips and the base of the tail—aka a butt.

The actual description of the butthole, which appears in a paper that hasn’t yet been peer-reviewed, makes me have sympathy for a dinosaur that probably didn’t expect to have its posterior formally presented in the technical literature over 100 million years after its death. On the fossil, just below the tail, the butthole appears as a “blackish mottled ovoid area,” the paleontologists write (the image is on Page 4 of the PDF, found at this link). To the naked eye, the spot looks like a series of dark, stacked bands running between the base of the tail and hip bones, clearly different from the skin around it.

*snip*

I tried to keep from posting this, but my 12 year old self won.