Brontotholus harmoni

Brontotholus is an extinct genus of pachycephalosaurid dinosaur known from the Late Cretaceous Two Medicine and Oldman formations of Montana, United States, and Alberta, Canada, respectively. The genus contains a single species, Brontotholus harmoni, known from multiple partial domes.

Brontotholus harmoni

Connor Ashbridge · CC BY 4.0 · via Wikidata/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.

On record

Recorded, not inferred
Sits inside
BrontotholusPBDB
Diet
herbivorePBDB, for Ornithischia
Life habit
ground dwelling, gregariousPBDB, for Ornithischia
Motility
actively mobilePBDB, for Ornithischia
Environment
terrestrialPBDB, for Ornithischia

Time the record covers

At most 12 million years on record.

Every occurrence read is dated to somewhere between 83.6 Mya and 72.2 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.

Late Cretaceous — about 3 of 3 occurrencesLate Cretaceous84–83 Mya — about 0.1 occurrences83–83 Mya — about 0.1 occurrences83–82 Mya — about 0.1 occurrences82–82 Mya — about 0.1 occurrences82–82 Mya — about 0.1 occurrences82–81 Mya — about 0.1 occurrences81–81 Mya — about 0.1 occurrences81–80 Mya — about 0.1 occurrences80–80 Mya — about 0.1 occurrences80–80 Mya — about 0.1 occurrences80–79 Mya — about 0.1 occurrences79–79 Mya — about 0.1 occurrences79–78 Mya — about 0.1 occurrences78–78 Mya — about 0.1 occurrences78–77 Mya — about 0.1 occurrences77–77 Mya — about 0.1 occurrences77–77 Mya — about 0.1 occurrences77–76 Mya — about 0.1 occurrences76–76 Mya — about 0.1 occurrences76–75 Mya — about 0.1 occurrences75–75 Mya — about 0.1 occurrences75–75 Mya — about 0.1 occurrences75–74 Mya — about 0.1 occurrences74–74 Mya — about 0.1 occurrences74–73 Mya — about 0.1 occurrences73–73 Mya — about 0.1 occurrences73–73 Mya — about 0.1 occurrences73–72 Mya — about 0.1 occurrences84.1 Mya71.7 Mya

3 occurrences of Brontotholus harmoni on record, most of them in the Late Cretaceous. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.

When

3 occurrences

These are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.

Found in

2 formations

Two Medicine — 48.97°N, 112.64°WTwo Medicine — 48.91°N, 112.64°WOldman — 49.07°N, 110.45°W

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The named rock units Brontotholus harmoni has been recovered from, largest first. Drawn where the rock is now, not where it formed.

Brontotholus harmoni and its relatives

Late Cretaceous

Where Brontotholus harmoni and its relatives were recorded in the Late Cretaceous.

Found in the same rock

4 taxa

The Paleobiology Database records 3 sites for Brontotholus harmoni, and this reads all of them. The number is how many of those sites it was catalogued from too.

This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.

Entered from

1 reference

Each of the 3 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. Each entry links to doi.org. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.

Media and terms

Media content1

Picture of Brontotholus harmoni

Credit
Connor Ashbridge
Licence
CC BY 4.0
Commercial use
the licence allows it

No 3D scan of Brontotholus harmoni was found in MorphoSource and Sketchfab.

Smithsonian Open Access was not reached for this taxon, so this list is what the others held rather than everything there is.

The description on this site

Licence
CC BY-SA 4.0

This is what the site found, which is not the same as what exists.

Keep going

What may have been alongside itBrontotholus through timeFormations of the Late CretaceousThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Woodruff et al. 2025