Table 1: The times of first appearance (FAD) and last appearance (LAD) for some groups of dinosaurs. Use this chart to answer the questions below. Group Earliest Geologic Period Earliest Geologic Age FAD (Ma) Latest Geologic Period Latest Geologic Age LAD (Ma) Stegosauria Jurassic Callovian 166 Cretaceous Coniacian 86 Ornithopoda Jurassic Sinemurian 199 Cretaceous Maastrichtian 66 Ankylosauria Jurassic Callovian 166 Cretaceous Maastrichtian 66 Ceratopsia Jurassic Tithonian 152 Cretaceous Maastrichtian 66 Pachycephalosauria Jurassic Tithonian 152 Cretaceous Maastrichtian 66 Sauropoda Triassic Carnian 237 Cretaceous Maastrichtian 66 Theropoda Triassic Landianian 242 Cretaceous Maastrichtian 66 Utahraptor
(genus) Cretaceous Hautervian 130 Cretaceous Barremian 125 Tyrannosaurus
(genus) Cretaceous Maastrichtian 68 Cretaceous Maastrichtian 66 Triceratops
(genus) Cretaceous Maastrichtian 68 Cretaceous Maastrichtian 66 Iguanodon
(genus) Cretaceous Barremian 126 Cretaceous Aptian 122 1.
If you found a deposit containing specimens of BOTH Stegosauria and Ornithopoda, what is the potential age range (maximum and minimum age in millions of years, Ma) of that deposit? 2.
If you found a deposit containing specimens of Pachycephalosauria AND Sauropoda, what is the oldest possible age (in millions of years) of that deposit? 3.
If you found both Utahraptor
and Iguandon
in the same deposit, what is the potential age range (maximum and minimum age, in millions of years) of that deposit? 4.
In a popular film, Utahraptor
and Tyrannosaurus
have a scene together. Would this have been possible in the real world? Provide your evidence and explain your reasoning. 5.
In an even older popular animated film, Triceratops
co-stars with a sauropod.
Would this have been possible in the real world? Provide your evidence and explain your reasoning. 6.
Why might we use genera in biostratigraphy rather than broader taxonomic groups? 7.
Did all non-avian dinosaur groups go extinct at the Maastrichtian? Which went extinct before the Maastrichtian? The maximum age is 86 Ma which is the LAD of the Stegosauria and the minimum is the FAD of the Ornithopoda which is 199 Ma.
The deposit cannot be any older than 66 million years due to the fact that both specimens share the same LAD of 66
The maximum would be the Utahraptor's LAD of 125 and the minimum would be 126 Ma which is the Iguanadon's FAD. Therefore the potential age range is 1million years,
This is not possible since they did not live at the same time. The Utahraptor's LAD 125 Ma whereas the Tyrannosaurus didn't even show up until 68 Ma. The Utahraptor went extinct before the Tyrannosaurus was even alive so therefore they could not have crossed paths.
This is possible because both species share the same latest geological age and period. They also have the same LAD of 66. These reasons show that they could have crossed paths at some point.
Genera is a more specific tool than taxonomic groups. Genera can provide more detailed information and helps to get more of an exact answer. This makes it better to use for biostratigraphy.
Not all non-avain dinosaurs went extinct during the Maastrichtian. The dinosaurs that went extinct before that period are the Utahraptor, the Stegosauria, and the Iguanadon.
