Deep Time Detective
Dinosaurs did not all live at the same time. Become a deep-time investigator in this free dinosaur timeline game: compare fossil ranges with rock-layer clues and capture the complete age window that fits every observation. Six cases build from familiar Jurassic dinosaurs to narrower geological deductions.
Deep Time Detective
Capture the evidence, one age window at a time
How to play the dinosaur timeline puzzle
- Read every evidence card in the current case. Each card gives a possible age interval in millions of years ago.
- Move the younger edge and older edge to select the entire interval shared by every card. The largest younger limit sets one edge; the smallest older limit sets the other.
- Use the sliders, the one-step buttons, or the age number fields. Keyboard users can Tab between controls and use arrow keys on a slider.
- Verify your age window. A correct answer earns a field stamp and unlocks the next case. An incorrect answer explains which edge needs revision.
- You have three checks per case and no countdown. If the checks run out, review the overlap and retry the same case while keeping earlier completed cases.
How do scientists estimate a dinosaur fossil’s age?
In a sequence of undisturbed deposited layers, lower layers formed before the layers above them. This principle, superposition, helps establish relative ages. The puzzle uses invented ash brackets as one line of evidence; they are not measurements from real field sites. Read the National Park Service explanation of superposition.
Numerical dating adds a different kind of evidence. Radiometric methods can estimate the ages of suitable minerals, including material in volcanic ash associated with sedimentary layers. Combining several observations can narrow a possible age interval. Explore the National Park Service guide to geological dating.
Jurassic dinosaurs and the end of the Cretaceous
The game uses the Natural History Museum’s reference ranges of approximately 152–145 million years ago for both Stegosaurus and Diplodocus. For Tyrannosaurus rex, it uses the Smithsonian’s approximately 68–66 million year range. That puts T. rex much later than those Jurassic giants. Read the Smithsonian T. rex fact sheet.
The period boundaries are rounded for learning: Triassic 252–201, Jurassic 201–145, and Cretaceous 145–66 million years ago. Dates in scientific references may be more precise and can change as evidence improves. See the Natural History Museum’s dinosaur time guide.
Why use a range instead of a single date?
A fossil record gives evidence about a span of time rather than an exact birthday for a dinosaur species. In this puzzle, a verified window means all the rounded clues agree. It does not prove a real fossil’s age, that two individuals met, or that overlapping dinosaurs lived in the same place. The dated ash beds, sample descriptions, and regional cross-checks are fictional teaching cases.