The longest and shortest dinosaur fossil ranges
Megalosaurus has the longest fossil range on this site, 55 million years (168.2–113.2 Ma), just ahead of Thecodontosaurus at 54.3. The shortest belong to Brontosaurus and Kentrosaurus, each confined to the Tithonian, a stage 4.2 million years long. Neither end of the list is a clean measure of how long a genus existed. Long ranges usually come from a few far-flung records, and short ones from a short stage.
The ten longest ranges
| # | Genus | Range (Ma) | Stages | Length (My) | Records |
|---|---|---|---|---|---|
| 1 | Megalosaurus | 168.2–113.2 | Bathonian–Aptian | 55 | 57 |
| 2 | Thecodontosaurus | 247.2–192.9 | Anisian–Sinemurian | 54.3 | 14 |
| 3 | Cetiosaurus | 168.2–125.77 | Bathonian–Hauterivian | 42.4 | 30 |
| 4 | Coelurus | 149.2–113.2 | Tithonian–Aptian | 36 | 14 |
| 5 | Carcharodontosaurus | 121.4–93.9 | Aptian–Cenomanian | 27.5 | 44 |
| 6 | Psittacosaurus | 125.77–100.5 | Barremian–Albian | 25.3 | 70 |
| 7 | Mamenchisaurus | 165.3–145 | Callovian–Tithonian | 20.3 | 23 |
| 8 | Neuquensaurus | 86.3–66 | Santonian–Maastrichtian | 20.3 | 15 |
| 9 | Omeisaurus | 165.3–145 | Callovian–Tithonian | 20.3 | 13 |
| 10 | Mantellisaurus | 132.6–113.2 | Hauterivian–Aptian | 19.4 | 17 |
Length is the time from the base of the first stage to the top of the last. Records are PBDB occurrences, including synonyms.
Why the longest are long
Look at how the records are spread, not at the length alone. Megalosaurus has 57 records from 7 countries and at least 10 formations, and its dated records fall in 10 different stages, from the Bajocian to the Albian. Its range adds up finds from many places and many layers of rock, and it should be read as a summary of all of them rather than as the history of one population.
Coelurus shows how much a handful of records can do. Of its 14 dated records, 11 are from the Tithonian. Just 2 are from the Aptian, but that is more than the tenth of records the method sets aside, so the range runs on to 113.2 million years ago and reaches 36 million years in all. Cetiosaurus is similar: 21 of its 29 dated records are Bathonian, yet 4 younger records in the Hauterivian and Barremian pull its range forward to 125.77 Ma.
Thecodontosaurus rests on only 14 records, spread over 5 stages from the Anisian to the Sinemurian. With so few records, the 10th and 90th percentiles sit close to the oldest and youngest, and the range stays wide.
Why the shortest are short
All of the shortest ranges are single stages, and the shortest stages decide the order. Brontosaurus (Tithonian, 4.2), Kentrosaurus (Tithonian, 4.2), Plateosaurus (Rhaetian, 4.3) and Phuwiangosaurus (Barremian, 4.4) head the list. The Mesozoic stages vary a lot in length: the Norian lasted 21.3 million years, the Induan only 0.7. No genus here is confined to either of those two, but among the 46 single-stage genera the range still runs from 4.2 million years (Tithonian) to 11.5 (Campanian).
| Genus | Range (Ma) | Stage | Length (My) | Records |
|---|---|---|---|---|
| Brontosaurus | 149.2–145 | Tithonian | 4.2 | 23 |
| Kentrosaurus | 149.2–145 | Tithonian | 4.2 | 27 |
| Plateosaurus | 205.7–201.4 | Rhaetian | 4.3 | 36 |
| Phuwiangosaurus | 125.77–121.4 | Barremian | 4.4 | 15 |
| Alamosaurus | 72.1–66 | Maastrichtian | 6.1 | 38 |
| Ankylosaurus | 72.1–66 | Maastrichtian | 6.1 | 16 |
| Edmontosaurus | 72.1–66 | Maastrichtian | 6.1 | 85 |
| Gallimimus | 72.1–66 | Maastrichtian | 6.1 | 30 |
Short ranges are not necessarily thin records. Brontosaurus has 23 records and Kentrosaurus 27, close to the median of 25 for all 99 genera, and Edmontosaurus, confined to the Maastrichtian, has 85. What makes a range short is that the dated records fall in one short stage.
Do more fossils mean a longer range?
Hardly at all. Across the 99 genera, the correlation between the number of fossil records and the length of the range is -0.05, close to zero. The median range barely moves between genera with few records and genera with many:
| Fossil records | Genera | Median range (My) |
|---|---|---|
| 12–19 | 35 | 11.5 |
| 20–39 | 38 | 10.65 |
| 40–79 | 16 | 10.65 |
| 80 or more | 10 | 9.8 |
The best-recorded genera tend to come from one rich formation in one or two stages, so more records simply fill the same stages more densely. Triceratops, with 166 records, has a range of 6.1 million years.
By group
| Group | Genera | Median range (My) | Longest |
|---|---|---|---|
| Theropods | 32 | 11.5 | Megalosaurus (55) |
| Ornithopods | 21 | 11.5 | Mantellisaurus (19.4) |
| Horned dinosaurs | 11 | 11.5 | Psittacosaurus (25.3) |
| Armoured & plated dinosaurs | 14 | 10.65 | Polacanthus (18.4) |
| Sauropodomorphs | 19 | 9.8 | Thecodontosaurus (54.3) |
| Dome-headed dinosaurs | 2 | 8.8 | Stegoceras (11.5) |
The medians sit close together, between 8.8 and 11.5 million years, close to the length of the Campanian (11.5) or of the Kimmeridgian and Tithonian together (9.8). The long ranges are individual cases rather than a trait of any group. The rankings page lists the 15 longest, and every genus page shows where its own range falls among all 99.
Sources
- The Paleobiology Database (paleobiodb.org), data service v1.2, licensed CC BY 4.0; retrieved 2026-10-27. All counts, ranges and pairs in this article are calculated by FossilRange from that download.
- International Commission on Stratigraphy, International Chronostratigraphic Chart: stage names, base ages and colours.
- FossilRange, Data & method: which genera are included and how ranges are derived.