In most books, Triceratops is listed to live between 68-66 MYA (million years ago), however some books list Triceratops as living between 70-66 MYA. The Campanian age ended about 72 MYA and then came the Maastrichtian. Many articles state that Triceratops is "late Maastrichtian" dinosaur. All these citations do not give a clear answer: when did Triceratops live? All sources agree that Triceratops lived up to the K-Pg extinction 66 MYA, but when did the earliest Triceratops live?

This may be vague question so put it more empirically: what is the oldest age that a Triceratops fossil is dated to? Not when the first fossil of Triceratops was found but what is the earliest age (in MYA) at which Triceratops are known to have existed? Are there Triceratops fossils from 68 MYA? And from 70 MYA?

  • $\begingroup$ late Maastrichtian, Maastricht is the name of a restaurant. $\endgroup$
    – John
    Jul 21, 2019 at 19:45
  • $\begingroup$ Thanks. From where I am coming from, the term localized as "Maastricht" but thank you for your comment how it is used in general/international. $\endgroup$ Jul 26, 2019 at 14:24

1 Answer 1


late Maastrichtian is probably it.

Part of the problem you are running into is the Triceratops genus is in flux, there is debate about whether certain species belong in the genus. Such as whether triceratops and torosaurus are the same species.

The other problem you are running in to is the accuracy of dating methods, many fossils are dated indirectly, by bracketing (distance in section) with ash beds but this means they have a decent margin of error, 69MYA +/- 2mya is completely possible. Many were collected before such dating was even done or suche detailed measurements were taken leading to an even wider error bar. Especially given the best dates for the Hell Creek Formation itself has an date range error of about +/- 0.7MY and begins with a unconformity. Many studies are just going not going to calculate a date that has a high degree of uncertainty. The date for the end is more solid because it is an ash bed, thus directly datatable.

The most recent analysis of triceratops I know of is here many of the specimens were collected in the 1800's so late Maastrichtian is about the best you are going to get for an uncontroversial date.


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