Heterastridium

Heterastridium is an extinct genus of marine hydrozoan. It is the only accepted genus in the monotypic family Heterastridiidae. The fossils date from the Upper Triassic. They are mostly discoid or spherical and some forms found in the Karakorum mountains are called Karakorum stones. They vary in diameter from 1 to 35 cm and appear to follow Cope's rule for the prehistoric climate.

Heterastridium

W T Blanford · Public Domain · 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
HeterastrididaePBDB
Diet
carnivore, suspension feederPBDB, for Hydrozoa
Life habit
epifaunalPBDB, for Hydrozoa
Motility
stationary, attachedPBDB, for Hydrozoa
Vision
blindPBDB, for Hydrozoa

Time the record covers

At least 54 million years on record.

The record covers at least 259.857 Mya to 205.7 Mya. No occurrence read is dated outside 266.9 Mya to 201.4 Mya.

Permian — about 2 of 56 occurrencesPermianEarly Triassic — about 0 of 56 occurrencesMiddle Triassic — about 0 of 56 occurrencesLate Triassic — about 54 of 56 occurrencesLate TriassicEarly Jurassic — about 0 of 56 occurrences268–266 Mya — about 0.1 occurrences266–264 Mya — about 0.3 occurrences264–261 Mya — about 0.3 occurrences261–259 Mya — about 0.2 occurrences255–252 Mya — about 0.8 occurrences252–250 Mya — about 0.2 occurrences239–236 Mya — about 0.3 occurrences236–234 Mya — about 1 occurrence234–232 Mya — about 1 occurrence232–230 Mya — about 1 occurrence230–227 Mya — about 1 occurrence227–225 Mya — about 3 occurrences225–223 Mya — about 3 occurrences223–221 Mya — about 3 occurrences221–218 Mya — about 3 occurrences218–216 Mya — about 3 occurrences216–214 Mya — about 4 occurrences214–211 Mya — about 4 occurrences211–209 Mya — about 7 occurrences209–207 Mya — about 7 occurrences207–205 Mya — about 6 occurrences205–202 Mya — about 4 occurrences202–200 Mya — about 2 occurrences259.857 Mya205.7 Mya268 Mya200 Mya

56 occurrences of Heterastridium on record, most of them in the Late Triassic. 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

56 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

10 formations

Nayband — 32.37°N, 57.47°ENayband — 32.93°N, 52.03°ENayband — 33.02°N, 52.25°ENayband — 34.06°N, 58.08°ENayband — 33.07°N, 52.03°EKamishak — 57.72°N, 155.30°WKamishak — 59.78°N, 154.50°WAntimonio — 30.72°N, 112.55°WDachstein — 47.50°N, 13.50°EDachstein — 48.00°N, 16.42°ECephalopod Limestone — 10.30°S, 123.71°ECephalopod Limestone — 9.83°S, 124.57°EBortepa — 37.50°N, 74.50°EHouziguan Limestone — 25.75°N, 106.17°EChangxing — 25.83°N, 106.08°EGhalilah — 25.60°N, 56.06°ELeprédour Shellbed — 22.00°S, 166.05°E

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The named rock units Heterastridium has been recovered from, largest first. Drawn where the rock is now, not where it formed. 35 occurrences have no formation on record, which is common for older literature.

Heterastridium and its relatives

Late Triassic

Where Heterastridium and its relatives were recorded in the Late Triassic.

Found in the same rock

378 taxa

The Paleobiology Database records 52 sites for Heterastridium, 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 56 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 content1

Picture of Heterastridium

Credit
W T Blanford
Licence
Public Domain
Commercial use
the licence allows it

No 3D scan was found. Smithsonian Open Access, MorphoSource and Sketchfab were all searched.

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 itHeterastrididae through timeFormations of the Late TriassicThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Reuss 1865