Hemicyclaspis

Searched as Hemicyclaspis lightbodii. The Paleobiology Database treats Hemicyclaspis as the accepted name.

Hemicyclaspis is an extinct genus of primitive jawless fish, closely related to Cephalaspis, that lived in the Late Silurian (Pridoli) to Devonian period in what is now Europe and North America. A typical cephalaspid, Hemicyclaspis had a heavily armored, shovel-shaped headshield. It is thought to have been a better swimmer than most of its relatives because of its powerful tail, stabilizing dorsal fin and the keel-shaped hydrodynamic edges of its head shield. Hemicyclaspis probably foraged the ocean floor for food.

Hemicyclaspis

the paleobear · 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
AteleaspididaePBDB
Motility
actively mobilePBDB, for Chordata

Time the record covers

At most 3.1 million years on record.

The one occurrence read is dated to somewhere between 422.7 Mya and 419.62 Mya, which is a dating window rather than a span.

Silurian — about 1 of 1 occurrenceSilurianDevonian — about 0 of 1 occurrence423–423 Mya — about 0.0 occurrences423–423 Mya — about 0.0 occurrences423–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–422 Mya — about 0.0 occurrences422–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–421 Mya — about 0.0 occurrences421–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences420–420 Mya — about 0.0 occurrences423.2 Mya419.12 Mya

1 occurrence of Hemicyclaspis 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

1 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

1 formation

Temeside Shale — 52.37°N, 2.73°W

Loading coastlines…

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

Hemicyclaspis and its relatives

Silurian

Where Hemicyclaspis and its relatives were recorded in the Silurian.

Found in the same rock

64 taxa

The Paleobiology Database records 7 sites for Hemicyclaspis, 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

1 reference

Each of the 1 occurrence 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 the Paleobiology Database's own record for the work.

Media and terms

Media content2

Picture of Hemicyclaspis

Credit
the paleobear
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

Smithsonian Open Access and MorphoSource were 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 itAteleaspididae through timeFormations of the SilurianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Lankaster 1870