Notostraca

The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, with similar forms having existed since the end of the Devonian, around 360 million years ago. They have a broad, flat carapace, which conceals the head and bears a single pair of compound eyes. The abdomen is long, appears to be segmented and bears numerous pairs of flattened legs. The telson is flanked by a pair of long, thin caudal rami. Phenotypic plasticity within taxa makes species-level identification difficult, and is further compounded by variation in the mode of reproduction. Notostracans are omnivores living on the bottom of temporary pools and shallow lakes.

Notostraca

NalesnikLD · 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
Also called
tadpole shrimpPBDB
Sits inside
CalmanostracaPBDB
Diet
suspension feeder, detritivorePBDB, for Branchiopoda
Life habit
nektobenthicPBDB, for Branchiopoda
Motility
slow-movingPBDB, for Branchiopoda
Vision
well-developedPBDB, for Branchiopoda
Environment
marine,brackish,freshwaterPBDB, for Branchiopoda

Time the record covers

At least 356 million years on record.

The record covers at least 358.86 Mya to 2.58 Mya. No occurrence read is dated outside 365.2 Mya to 11.7 ka.

Devonian — about 1 of 12 occurrencesCarboniferous — about 2 of 12 occurrencesCarboniferousPermian — about 1 of 12 occurrencesPermianEarly Triassic — about 0 of 12 occurrencesMiddle Triassic — about 3 of 12 occurrencesLate Triassic — about 0 of 12 occurrencesEarly Jurassic — about 0 of 12 occurrencesMiddle Jurassic — about 2 of 12 occurrencesLate Jurassic — about 0 of 12 occurrencesEarly Cretaceous — about 2 of 12 occurrencesEarly CretaceousLate Cretaceous — about 0 of 12 occurrencesPaleocene — about 0 of 12 occurrencesEocene — about 0 of 12 occurrencesOligocene — about 0 of 12 occurrencesMiocene — about 0 of 12 occurrencesPliocene — about 0 of 12 occurrencesPleistocene — about 1 of 12 occurrences373–360 Mya — about 0.8 occurrences360–348 Mya — about 0.2 occurrences335–323 Mya — about 0.1 occurrences323–310 Mya — about 0.9 occurrences310–298 Mya — about 1 occurrence273–261 Mya — about 0.8 occurrences261–248 Mya — about 0.2 occurrences248–236 Mya — about 3 occurrences174–161 Mya — about 2 occurrences137–124 Mya — about 0.7 occurrences124–112 Mya — about 1 occurrence12–0 Mya — about 1 occurrence358.86 Mya2.58 Mya373 Mya0 Mya

12 occurrences of Notostraca on record, most of them in the Middle Triassic. The Paleobiology Database records this as a living group. 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

12 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

Grès à Voltzia — 48.58°N, 7.49°EGrès à Voltzia — 48.78°N, 7.25°EYixian — 41.03°N, 118.92°EYixian — 42.20°N, 116.48°EUkureyskaya — 52.52°N, 116.72°EPradineaux — 43.51°N, 6.63°EOttweiler Schichten — 49.37°N, 7.18°EEvieux — 50.45°N, 5.06°EVoltzia — 48.58°N, 7.49°E

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The named rock units Notostraca has been recovered from, largest first. Drawn where the rock is now, not where it formed. 2 occurrences have no formation on record, which is common for older literature.

Notostraca and its relatives

Middle Triassic

Where Notostraca and its relatives were recorded in the Middle Triassic.

Found in the same rock

130 taxa

The Paleobiology Database records 12 sites for Notostraca, 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

8 references

Each of the 12 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 Notostraca

Credit
NalesnikLD
Licence
Public Domain
Commercial use
the licence allows it

No 3D scan of Notostraca 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 itCalmanostraca through timeFormations of the Middle TriassicThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Sars 1867