Psephoderma

Psephoderma is a genus of placodonts very similar to the related genera Placochelys and Cyamodus. Psephoderma had a flattened skull and a narrow, straight rostrum, much narrower than that of its relatives. Inside this skull, embedded in the jaws, were rounded teeth specialized for crushing the shellfish it ate. Unlike henodontid placodonts, Psephoderma's carapace was divided into two pieces, one on the shoulders and back, and another on the ventral end. Psephoderma grew to 180 centimetres (5.9 ft) long, larger than many of its relatives, and lived in the Late Triassic, about 210 million years ago. It was one of the last placodonts to live. Fossils of Psephoderma have been found in the Rhaetian deposits in the Alps and in England, hence the specific names.

Psephoderma

Tommy from Arad · 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
PlacochelyidaPBDB
Motility
actively mobilePBDB, for Osteichthyes
Environment
marinePBDB, for Sauropterygia
Length
1.8 mWikidata

Time the record covers

At least 35 million years on record.

The record covers at least 241.464 Mya to 205.7 Mya. No occurrence read is dated outside 243.43 Mya to 201.4 Mya.

Middle Triassic — about 2 of 10 occurrencesMiddle TriassicLate Triassic — about 8 of 10 occurrencesLate TriassicEarly Jurassic — about 0 of 10 occurrences244–243 Mya — about 0.5 occurrences243–241 Mya — about 1 occurrence241–240 Mya — about 0.4 occurrences240–238 Mya — about 0.1 occurrences217–215 Mya — about 0.1 occurrences215–214 Mya — about 0.3 occurrences214–212 Mya — about 0.3 occurrences212–211 Mya — about 0.2 occurrences206–205 Mya — about 1 occurrence205–203 Mya — about 2 occurrences203–202 Mya — about 2 occurrences202–201 Mya — about 1 occurrence241.464 Mya205.7 Mya244.3 Mya200.6 Mya

10 occurrences of Psephoderma 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

10 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

7 formations

Calcare di Zu — 45.83°N, 9.27°ECalcare di Zu — 45.77°N, 9.60°ECalcare di Zu — 45.82°N, 9.80°EKössener Schichten — 48.13°N, 16.24°EZorzino Limestone — 45.68°N, 9.72°EKössen — 47.05°N, 9.70°ESaharonim — 30.60°N, 34.82°EGevanim — 30.60°N, 34.82°EWestbury — 51.60°N, 2.63°W

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

Psephoderma and its relatives

Late Triassic

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

Found in the same rock

34 taxa

The Paleobiology Database records 9 sites for Psephoderma, 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

5 references

Each of the 10 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 Psephoderma

Credit
Tommy from Arad
Licence
CC BY 2.0
Commercial use
the licence allows it

No 3D scan of Psephoderma 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 itPlacochelyida through timeFormations of the Late TriassicThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. von Meyer 1858