Rhabdus rectius

Rhabdus rectius, also known as a straight tusk shell, is a species of scaphopod, a small marine mollusc native to the coast of central California whose shell, like that of all the members of its order, resembles a tusk. Most members of the scaphopoda have shells that exhibit a noticeable and characteristic anterior curvature— the shell of R. rectius, however, is unusually straight, hence the Latin word "rectius" in its binomial designation. R. rectius is a generalist carnivore found in shallow silty and sandy substrates. Aside from the usual diet of foraminiferans, it also eats sediment and fecal pellets. Its thin, straight shell becomes fragile when dehydrated. Some adult specimens are more than 10 centimetres (3.9 in) long, and have a maximum diameter of about 6 mm.

Rhabdus rectius

KDS4444 · CC BY-SA 4.0 · 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
Also called
straight tuskshellPBDB
Sits inside
RhabdusPBDB
Diet
deposit feederPBDB, for Dentaliida
Life habit
semi-infaunalPBDB, for Dentaliida
Motility
slow-movingPBDB, for Dentaliida
Vision
blindPBDB, for Scaphopoda

Time the record covers

At least 2.8 million years on record.

The record covers at least 3.6 Mya to 774 ka. No occurrence read is dated outside 5.333 Mya to 129 ka.

Miocene — about 0 of 4 occurrencesPliocene — about 3 of 4 occurrencesPliocenePleistocene — about 1 of 4 occurrencesPleistoceneHolocene — about 0 of 4 occurrences5.4–5.3 Mya — about 0.1 occurrences5.3–5.1 Mya — about 0.3 occurrences5.1–4.9 Mya — about 0.3 occurrences4.9–4.7 Mya — about 0.3 occurrences4.7–4.5 Mya — about 0.3 occurrences4.5–4.3 Mya — about 0.3 occurrences4.3–4.1 Mya — about 0.3 occurrences4.1–3.9 Mya — about 0.3 occurrences3.9–3.7 Mya — about 0.3 occurrences3.7–3.5 Mya — about 0.2 occurrences3.5–3.3 Mya — about 0.1 occurrences3.3–3.1 Mya — about 0.1 occurrences3.1–2.9 Mya — about 0.1 occurrences2.9–2.7 Mya — about 0.1 occurrences2.7–2.5 Mya — about 0.1 occurrences778 ka–583 ka Mya — about 0.3 occurrences583 ka–389 ka Mya — about 0.3 occurrences389 ka–194 ka Mya — about 0.3 occurrences194 ka–0 Mya — about 0.1 occurrences3.6 Mya774 ka5.8 Mya0 Mya

4 occurrences of Rhabdus rectius on record, most of them in the Pliocene. The Paleobiology Database records this as a living group, and the chart stops with its fossils rather than at the present. 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

Empire — 43.39°N, 124.28°WWildcat — 40.64°N, 124.31°WTowsley — 34.36°N, 118.51°WTimms Point Silt — 33.73°N, 118.28°W

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

Rhabdus rectius and its relatives

Pliocene

Where Rhabdus rectius and its relatives were recorded in the Pliocene.

Found in the same rock

91 taxa

The Paleobiology Database records 3 sites for Rhabdus rectius, 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. Each entry links to the Paleobiology Database's own record for the work.

Media and terms

Media content1

Picture of Rhabdus rectius

Credit
KDS4444
Licence
CC BY-SA 4.0
Commercial use
the licence allows it

No 3D scan of Rhabdus rectius 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 itRhabdus through timeFormations of the PlioceneThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. (Carpenter 1864)