A reconstruction of the only fossilised dinosaur cloaca in existence may help illuminate how the prehistoric animals mated.
The cloaca is an all-purpose opening on the body of many animals – including lizards, turtles and birds – that is used for mating, laying eggs, urinating and defecating.
In 2016, Jakob Vinther at the University of Bristol, UK, and his colleagues were assessing evidence of camouflage in the well-preserved skin of a metre-long horn-billed dinosaur called Psittacosaurus. They noticed that the animal also seemed to have a surprisingly intact cloaca.
Vinther and his colleagues took the fossil, flattened by years of compacting, and turned it from a 2D pancake into a 3D digital model. The team then tried to compare the Psittacosaurus’s cloaca against those of other animals.
Most birds, which evolved from dinosaurs, don’t have a penis and reproduce using “cloacal kissing”, im which cloacas touch. Vinther believes that Psittacosaurus didn’t do this. Its cloaca had two flaps of skin covering most of the cloacal vent, which gives it an appearance more like that of a crocodile’s cloaca rather than a bird’s. Male crocodiles have a penis that emerges from the cloaca and Vinther’s team suspects that Psittacosaurus did too. Vinther reckons the Psittacosaurus’s skin flaps could have hidden musk glands producing sexually attractive scents.
The conclusions mirror those reached by another team that analysed the same Psittacosaurus fossil and posted their findings to a preprint server last year.

What is it with theropod groups consisting of mostly-small species with one fuck-off-huge member?

Like, therizinosaurs were mostly 2-5 meters, and almost never surpassed a ton in weight. Except for Therizinosaurus, which was 10 meters and 3 tons.

Oviraptorosaurs generally were quite small, with most being less than 2 meters. And then in comes the 9-meter Gigantoraptor.

Ornithomimosaurs typically range in size from about turkey-sized to about ostrich-sized, but they also had Deinocheirus, which rivalled T. rex.

Huh. That’s disappointing. 

I checked the YouTubes, but apparently there’s no video of the cinematic evolution of T. rex noises. No comparison of the snarls from King Kong to Godzilla’s scream to the cries and hisses of Sharptooth to the gator noises of The Dinosaurs...finally shattering with the iconic Jurassic Park roar.

Youths today don’t get how powerful that noise was when it broke onto the scne. Heck, even the rancor in Star Wars was an icon of “giant toothy dinosaur” noises. It was new. It was creative and unlike any other sound in cinema.