
Maybe not. From ScienceDaily:
Dr. Jordan Mallon, a dinosaur specialist at the museum, argues instead that the fossil evidence for these distinctions is inconclusive and, as a result, it might be time to “rewrite the textbooks.” His report, published today in the online journal Paleobiology, focusses on the biological principle of sexual dimorphism, where males and females of a species can be distinguished based on physical characteristics other than sexual organs.
“I’m not saying that dinosaurs were not dimorphic, but I am saying that there’s no existing fossil evidence to suggest that they were. The jury is still out,” says Mallon.
Mallon made his assessment by revisiting previous studies attributing sexual dimorphism to dinosaurs. The problem, he explains, is that some of those studies not only relied on small sample sizes, but, more importantly, they did not properly analyze the statistical data, which led to invalid conclusions. (public access) Paper. – Jordan C. Mallon. Recognizing sexual dimorphism in the fossil record: lessons from nonavian dinosaurs. Paleobiology, 2017; 1 DOI: 10.1017/pab.2016.51 More.
Would preserved soft tissue help? As noted earlier, the exact role of sex as a strategy for procreation of complex life forms is unclear. Generally speaking, they use sexual reproduction but they get there by a variety of paths.
See also: Could a lamprey’s sex depend on food availability? Sex is a bit of a puzzle because it is a goal on which life forms seem to converge by many different ways. This one is different but logical.
And
Evolution appears to converge on goals—but in Darwinian terms, is that possible?
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