Trimerus

Trimerus is an extinct genus of trilobite in the family Homalonotidae. Trimerus is one of North America's largest trilobites, reaching over 20 cm (7.9 in) in length. It had a thorax composed of 13 segments with weak trilobation, a large subtriangular head terminating in an expanded rostral plate, a two-pronged hypostome, and a triangular pygidium. It is known from all continents except for Antarctica. Its tiny compound eyes and the shovel-like anterior of the head suggests a burrowing lifestyle, and an exoskeleton marked with many small pores which, in life, probably housed hair-like sensory setae in life, allowed the trilobite to feel which portions of its body were covered with sediment.

Trimerus

the paleobear from Lontananza, Loreto, Peru · CC BY 2.0 · via Wikipedia/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
HomalonotinaePBDB
Diet
carnivorePBDB, for Trilobita
Life habit
low-level epifaunalPBDB, for Trilobita
Motility
fast-movingPBDB, for Trilobita
Vision
well-developedPBDB, for Homalonotidae
Environment
marinePBDB, for Trilobita

Time the record covers

At least 56 million years on record.

The record covers at least 438.6 Mya to 382.31 Mya. No occurrence read is dated outside 443.1 Mya to 372.15 Mya.

Ordovician — about 0 of 72 occurrencesSilurian — about 46 of 72 occurrencesSilurianDevonian — about 26 of 72 occurrencesDevonian445–442 Mya — about 0.3 occurrences442–440 Mya — about 1 occurrence440–437 Mya — about 2 occurrences437–435 Mya — about 2 occurrences435–432 Mya — about 6 occurrences432–430 Mya — about 13 occurrences430–427 Mya — about 10 occurrences427–425 Mya — about 5 occurrences425–422 Mya — about 3 occurrences422–420 Mya — about 2 occurrences420–417 Mya — about 2 occurrences417–415 Mya — about 2 occurrences415–413 Mya — about 3 occurrences413–410 Mya — about 5 occurrences410–408 Mya — about 0.9 occurrences408–405 Mya — about 0.9 occurrences405–403 Mya — about 0.9 occurrences403–400 Mya — about 0.9 occurrences400–398 Mya — about 0.7 occurrences398–395 Mya — about 0.6 occurrences395–393 Mya — about 0.6 occurrences393–390 Mya — about 0.4 occurrences390–388 Mya — about 0.4 occurrences388–385 Mya — about 3 occurrences385–383 Mya — about 3 occurrences383–381 Mya — about 0.9 occurrences381–378 Mya — about 0.2 occurrences378–376 Mya — about 0.2 occurrences376–373 Mya — about 0.2 occurrences373–371 Mya — about 0.1 occurrences438.6 Mya382.31 Mya445 Mya371 Mya

72 occurrences of Trimerus on record, most of them in the Silurian. 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

72 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

25 formations

Rochester Shale — 43.15°N, 77.62°WRochester Shale — 43.15°N, 77.06°WRochester Shale — 43.10°N, 79.06°WRochester Shale — 43.00°N, 79.00°WRochester Shale — 43.17°N, 78.68°WRochester Shale — 43.15°N, 77.72°WRochester Shale — 43.22°N, 76.82°WRochester Shale — 39.65°N, 78.76°WRochester Shale — 39.57°N, 78.84°WJoslin Hill — 43.21°N, 75.46°WMount Ida — 34.08°S, 151.02°EMount Ida — 37.00°S, 144.00°EMount Ida — 36.77°S, 144.77°ELos Espejos — 30.25°S, 68.75°WLos Espejos — 30.00°S, 69.00°WMahantango — 40.50°N, 77.25°WMahantango — 40.05°N, 77.52°WMahantango — 40.33°N, 76.92°WLipeon — 24.00°S, 65.00°WLipeon — 24.50°S, 65.10°WMcIvor — 34.08°S, 151.02°EMcIvor — 37.00°S, 144.00°EWaldron Shale — 39.00°N, 86.00°WWaldron Shale — 39.45°N, 85.67°WCariy Sandstone — 25.00°S, 58.00°WRochester Shale — 43.12°N, 79.20°WRochester Shale — 43.03°N, 79.28°WIrondequoit Limestone — 43.21°N, 77.58°WHerkimer — 43.10°N, 75.23°WAnanea — 15.53°S, 68.73°WCatavi — 17.40°S, 66.15°WWayne — 36.08°N, 87.00°WHamar Laghdad Limestone — 31.38°N, 4.07°WKartal — 40.90°N, 29.18°EMaecuru — 2.00°S, 54.00°WRichea Siltstone — 43.00°S, 146.00°ECabezo Agudo — 41.13°N, 1.07°WReun Ar C'Hrank — 48.40°N, 4.48°WKeefer Sandstone — 39.63°N, 78.29°WRhydings — 52.67°N, 2.00°WWeltevrede — 33.33°S, 26.50°E

Loading coastlines…

The named rock units Trimerus has been recovered from, largest first. Drawn where the rock is now, not where it formed. One further formation holds fewer occurrences and is not listed. 6 occurrences have no formation on record, which is common for older literature.

Trimerus and its relatives

Silurian

Where Trimerus and its relatives were recorded in the Silurian.

Found in the same rock

629 taxa

The Paleobiology Database records 69 sites for Trimerus, and this reads all of them. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.

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

28 references

Each of the 72 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. 16 further references are not listed. Entries link to doi.org where the Paleobiology Database holds an identifier, and to its own record where it does not. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.

Media and terms

Media content2

Picture of Trimerus

Credit
the paleobear from Lontananza, Loreto, Peru
Licence
CC BY 2.0
Commercial use
the licence allows it

3D model

Source
Sketchfab
Licence
CC Attribution-NonCommercial
Commercial use
the licence does not allow it

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 itHomalonotinae through timeFormations of the SilurianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Green 1832