What rivers did dinosaurs drink from?
Rivers with no names, which nobody has ever seen, and which stopped flowing before there was anyone to name them. That sounds like a dead end — and then you find that the rock one of those rivers left behind is still there, about nineteen kilometres outside Denver, with 19 different kinds of animal recorded inside it.
A river you can still point at
When people record a fossil they also record what kind of place the rock was made in. For the collections around Denver the database uses words like “"channel"”, “fluvial indet.”, “channel lag” — a river channel, the moving water itself, filling with sand and whatever the current was carrying.
Here is what has been found in it:
- Apatosaurus louisae
- Stegosaurus
- Flagellicaudata
- Apatosaurus ajax
- Apatosaurinae
- Allosaurus
- Testudines
- Sauropoda
- Goniopholis felix
- Blechnum anceps
- Allantodiopsis erosa
- Dinosauria
- Diplodocus
- Diplodocidae
- Camarasaurus
- Theropoda
- Helochelydridae
- Ceratodontidae
- Stegosauria
Apatosaurus. Diplodocus. Allosaurus. Stegosaurus. The animals on the front of every dinosaur book, in rock that a river made.
🔴 But careful — this is the interesting part
Being found in a river’s rock is not the same as having drunk from that river. Rivers carry things. A bone can wash in from a long way upstream, sink, and be buried where it lands — and that is one of the commonest reasons bones survive at all. Moving water is a very good way to get buried quickly, which is what fossilisation needs.
So what the evidence honestly shows is: there were rivers, and there were dinosaurs, in the same place at the same time. Whether a particular Apatosaurus drank from a particular river is not something a fossil can tell you, and nobody should pretend otherwise — not even to make a better story.
Banks, swamps and the things that walked on them
Sixty million years later and a couple of kilometres away, the same database records different kinds of place: “levee”, “mire/swamp”. A levee is the raised bank a river builds beside itself when it floods. A mire is a swamp.
Of the 11 records from those places, 6 are not bones at all — they are names given to marks, the tracks of animals rather than the animals themselves. There is a crocodile in there too, which is the least surprising thing on this page.
- Ignotornis mcconnelli
- Hadrosauropodus leonardii
- Crocodylia
- Theropoda
- Ornithopoda
- Magnoavipes
What all of this is really telling you is that fresh water was ordinary. Rivers, banks, swamps, ponds — the same furniture as a landscape today, with different animals standing in it. Read what else that ground holds on the Denver page, or what the whole world looked like during the Jurassic.
Where this comes from
- The records
- Paleobiology Database, data service version data1.2, read . Licence: Creative Commons CC0. The words in quotation marks above — “channel”, “levee”, “mire/swamp” — are the database’s own, not ours. We did not decide any of these were rivers.
- How sure is this?
- The setting of each dig site is reconstructed from the rock by the people who recorded it, so it is an interpretation rather than an observation, and the ages are estimates with a range. Every distance is to where the fossil was dug up — near Denver, never underneath it.