10 Dinosaur Mysteries That Still Linger
Who was biggest and how they mated are still unknown
By Neal Colgrass, Newser Staff
Posted Aug 11, 2014 6:07 PM CDT
Updated Aug 11, 2014 6:17 PM CDT

(Newser) – Dinosaur articles, movies, and museum displays are common enough that you might consider all dino-mysteries solved, but the Smithsonian reports that major ones still remain. Among them:

  • Who was first? Nobody knows which dinosaur species came first, partly because fossil records provide fragmentary insights rather than "the entire reel," notes the Smithsonian. But skeletons in Tanzania and tracks in Poland tell us that dinosaurs may have started about 245 million years ago—with the slim and "dog-size" Nyasasaurus.
  • Hot- or cold-blooded? Several experts say dinosaurs were hot-blooded, but now some suggest they were "mesotherms," warming their bodies with their muscle activity and experiencing changing body temperatures.
  • Who was biggest? The fossil record isn't clear, but titanic sauropods evolved a few times into huge creatures like the Supersaurus, Diplodocus, and Argentinosaurus, each of which reached about 100 to 110 feet in length.
  • How did they mate? Well, they hatched from eggs. We assume females had a cloaca—an orifice that functions for reproduction, excretion, and urination in today's crocodiles and birds—and males had an "intromittent organ" found in ostriches and ducks. But we can't know without clear fossils of the organs.

Click for the full list, including the mystery of their "funky headgear," hunting habits, and, of course, how they went extinct. (Here's one theory on the latter.)

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Showing 3 of 14 comments
Aug 12, 2014 12:27 PM CDT
Who was first? Nobody knows, Nobody cares Hot- or cold-blooded? Nobody knows, Nobody cares Who was biggest? Nobody knows, Nobody cares How did they mate? Nobody knows, Nobody cares
The Pope
Aug 11, 2014 11:10 PM CDT
I want to know what Noah fed the dinosaurs when he had them on his ark?
Aug 11, 2014 11:09 PM CDT
Who was first? Gorgonopsian. (Or by other standards, Coelophysis). Hot- or cold-blooded? Cold. Who was biggest? Argentinosaurus. How did they mate? Sex.