Did Dinosaurs have Tits?

It is nice to speculate, is it not? A popular form of speculation is Science Fiction. Most of that is fiction, of course, very little is science. Most of SciFi poses the question 'what if?'. What if we could travel among the stars? What would we encounter? What if we could travel in time? What if we had teleportation devices? What if dinosaurs had not gone extinct, but evolved?

Selurian (with tits)

An example of the last question we find in the Doctor Who episode 'The Hungry Earth', wherein an humanoid and highly advanced species of dinosaurs called 'Selurians' have been hiding under ground all this time, sleeping, biding their time. Similarly, in an episode of Star Trek Voyager ('Ancient Origin') we find another species of humanoid dinosaurs, the Voth, who traveled to the stars before the meteorite hit that spelled the end of all dinosaurs. In both cases, the female dinosaurs are depicted with breasts.

Now, of course, that's utterly absurd. We know dinosaurs are more like lizards, lizards don't have breast (mammary glands or 'tits') and anyway, dinosaurs evolved into birds and birds don't have any tits either. So, should we dismiss the notion?

A Dinosaur (no tits)

Dinosaurs are not lizards. They may even have been warm-blooded, like birds and mammals. In fact, dinosaurs never went extinct: Birds are dinosaurs for all intents and purposes. But they only represent one branch of dinosaurs. There were other branches, all extinct now. Since dinosaurs were around for a very long time (much, much, longer than mammals...), they had plenty of opportunity to evolve into all sorts of things. They did not quite evolve into mammals per sé, but they did involve into Stegosaurus, which was similar to Dimetrodon, which was the ancestor of all modern mammals (but not really a dinosaur). 

I've made the handy-dandy diagram below to illustrate what modern species have tits and which ones don't and were the dinosaurs fit in the scheme of things. As you can see, they are somewhere in between the species with and without tits.

The evolution of tits over time

We also know that dinosaurs knew some form of parental care, although admittedly, we only know this from the bird-like dinosaurs. Birds and crocodiles also have parental care, and neither of them have tits. All dinosaurs laid eggs, like birds and crocodiles, but unlike lizards and amphibians, they laid their eggs on land. They could do this because they had evolved amniotic sacs, a membrane around the eggs that kept water in, but still allowed the embryo to breath. Our own babies also grow in amniotic sacs; that's the thing that actually breaks when we say that a pregnant woman's water breaks. Our 'eggs' develop inside a woman's womb. Platypus is the only remaining mammal that still lays eggs. Still, Platypus is a mammal, with tits to nourish its young. So parental care is no evidence of tits and eggs are no evidence against tits.

Dinosaurs are usually depicted with scales, like lizards, but we know now that many dinosaurs had feather-like hair and later species had actual feathers, like birds. As a matter of fact, the more we learn about dinosaurs, the less lizard-like the seem. Single filament feathers are a lot like hairs and it wouldn't surprise me if some evidence for furry dinosaurs would one day be uncovered. Fur must have developed at some time, why not in dinosaurs or their direct offspring? Nothing with only scales has tits, tits and fur seem to go together. Platypus has mostly fur, but has a scaly beak too; it's in-between. It's hard to say whether fur came before tits. Fur is rarely preserved and tits are never preserved (well, in ice-mummies, but those are quite recent).

Altogether, it seems unlikely that 'true' dinosaurs had tits. Their evolutionary cousins, the Synapsids, who developed into mammals, may have developed tits as well. At what stage this happened, is impossible to say. Quite recently, I suppose. After dinosaurs, but before Platypus. Platypus is itself a fully evolved species, very well-adapted. Elsewhere in the world, however, the Platypus-like creatures that used to roam the earth have gone extinct. Simply because laying eggs on the ground is rather hazardous if you can't fly and there are hungry mammals about (see also the Dodo). Birds still lay eggs because they can fly. No need to evolve much, once you've mastered that trick!

In conclusions: Dinosaurs did not have tits and it seems unlikely that if they did stick around somewhere, they would have grown a pair through convergent evolution. They might have evolved life-birth, but they would still have puked some pre-digested food into the mouths of their young, just like birds, rather than feed them with milk.

July 3, update: I noticed this article today (published yesterday). Traces of furry-feathers have been discovered on a remarkably well-preserved dinosaur fossil from Germany. This proves that feathers were more wide-spread on dinosaurs than previously thought (most feathered dinosaur fossils were found in China). Still no tits, though. In time, perhaps!