Galeaspida

Galeaspida is an extinct taxon of jawless marine and freshwater fish. The name is derived from galea, the Latin word for helmet, and refers to their massive bone shield on the head. Galeaspida lived in shallow, fresh water and marine environments during the Silurian and Devonian times in what is now Southern China, Tibet and Vietnam. Superficially, their morphology appears more similar to that of Heterostraci than Osteostraci, there being currently no evidence that the galeaspids had paired fins. A galeaspid Tujiaaspis vividus from the Silurian period of China was described in 2022 as having a precursor condition to the form of paired fins seen in Osteostraci and gnathostomes. Earlier than this, Galeaspida were already in fact regarded as being more closely related to Osteostraci, based on the closer similarity of the morphology of the braincase.

Galeaspida

Apokryltaros at English Wikipedia · CC BY-SA 3.0 · 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
VertebrataPBDB
Motility
actively mobilePBDB, for Chordata

Time the record covers

At least 13 million years on record.

The record covers at least 432.9 Mya to 419.62 Mya. No occurrence read is dated outside 438.6 Mya to 413.02 Mya.

Silurian — about 3 of 4 occurrencesSilurianDevonian — about 1 of 4 occurrencesDevonian439–438 Mya — about 0.1 occurrences438–437 Mya — about 0.3 occurrences437–436 Mya — about 0.3 occurrences436–436 Mya — about 0.3 occurrences436–435 Mya — about 0.3 occurrences435–434 Mya — about 0.3 occurrences434–433 Mya — about 0.3 occurrences433–432 Mya — about 0.0 occurrences423–422 Mya — about 0.1 occurrences422–421 Mya — about 0.3 occurrences421–420 Mya — about 0.3 occurrences420–420 Mya — about 0.3 occurrences420–419 Mya — about 0.1 occurrences419–418 Mya — about 0.1 occurrences418–417 Mya — about 0.1 occurrences417–416 Mya — about 0.1 occurrences416–415 Mya — about 0.1 occurrences415–414 Mya — about 0.1 occurrences414–413 Mya — about 0.1 occurrences413–413 Mya — about 0.1 occurrences432.9 Mya419.62 Mya439.1 Mya412.5 Mya

4 occurrences of Galeaspida 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

4 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

4 formations

Xitun — 25.49°N, 103.80°EYulongsi — 25.45°N, 103.77°ETataaiertage — 40.54°N, 78.98°EXikeng — 29.41°N, 115.43°E

Loading coastlines…

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

Galeaspida and its relatives

Silurian

Where Galeaspida and its relatives were recorded in the Silurian.

Found in the same rock

54 taxa

The Paleobiology Database records 2 sites for Galeaspida, 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

4 references

Each of the 4 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. 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 content1

Picture of Galeaspida

Credit
Apokryltaros at English Wikipedia
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

No 3D scan of Galeaspida was found in Sketchfab.

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 itVertebrata through timeFormations of the SilurianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Liu 1965