Megacheira

Megacheira is an extinct class of early Paleozoic predatory arthropods defined by their possession of spined "great appendages". Their taxonomic position is controversial, with studies generally either considering them stem-group euarthropods, or stem-group chelicerates. The homology of the great appendages to the cephalic appendages of other arthropods is also controversial. Uncontested members of the group were present in marine environments worldwide from the lower Cambrian to the upper Ordovician.

Megacheira

Junnn11 · 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
Sits inside
DeuteropodaPBDB
Motility
actively mobilePBDB, for Arthropoda

Time the record covers

At least 83 million years on record.

The record covers at least 516 Mya to 432.9 Mya. No occurrence read is dated outside 521 Mya to 426.7 Mya.

Cambrian — about 118 of 121 occurrencesCambrianOrdovician — about 2 of 121 occurrencesOrdovicianSilurian — about 1 of 121 occurrencesSilurian523–520 Mya — about 13 occurrences520–516 Mya — about 30 occurrences516–513 Mya — about 9 occurrences513–510 Mya — about 2 occurrences510–507 Mya — about 39 occurrences507–503 Mya — about 18 occurrences503–500 Mya — about 5 occurrences500–497 Mya — about 4 occurrences471–467 Mya — about 0.2 occurrences467–464 Mya — about 0.3 occurrences464–461 Mya — about 0.3 occurrences461–458 Mya — about 0.2 occurrences454–451 Mya — about 0.2 occurrences451–448 Mya — about 0.4 occurrences448–444 Mya — about 0.3 occurrences435–431 Mya — about 0.3 occurrences431–428 Mya — about 0.5 occurrences428–425 Mya — about 0.2 occurrences516 Mya432.9 Mya523 Mya425 Mya

121 occurrences of Megacheira on record, most of them in the Cambrian. 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

121 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

15 formations

Burgess Shale — 51.44°N, 116.47°WBurgess Shale — 51.39°N, 116.43°WYuanshan — 24.81°N, 102.58°EYuanshan — 24.67°N, 102.65°EYuanshan — 24.84°N, 102.41°EYuanshan — 25.40°N, 103.38°EYuanshan — 25.72°N, 103.99°EYu'anshan — 25.33°N, 103.50°EYu'anshan — 24.77°N, 102.58°EQiongzhusi — 24.65°N, 102.97°EQiongzhusi — 24.68°N, 102.98°EQiongzhusi — 24.63°N, 102.95°EQiongzhusi — 24.72°N, 102.95°EMarjum — 39.25°N, 113.36°WMarjum — 39.27°N, 113.31°WWheeler Shale — 39.31°N, 113.29°WBalang — 28.42°N, 109.42°ELead Bell Shale — 42.00°N, 112.00°WLangston — 41.59°N, 112.04°WWulongqing — 24.95°N, 102.80°EStephen — 51.45°N, 116.32°WMarsden Sandstone — 35.58°S, 137.50°EGilwern Volcanic — 52.24°N, 3.38°WWeeks — 39.22°N, 113.40°WUtica Shale — 43.21°N, 75.46°W

Loading coastlines…

The named rock units Megacheira has been recovered from, largest first. Drawn where the rock is now, not where it formed. 1 occurrence has no formation on record, which is common for older literature.

Megacheira and its relatives

Cambrian

Where Megacheira and its relatives were recorded in the Cambrian.

Found in the same rock

800 taxa

The Paleobiology Database records 76 sites for Megacheira, 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

21 references

Each of the 121 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. 9 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 Megacheira

Credit
Junnn11
Licence
CC BY-SA 4.0
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 itDeuteropoda through timeFormations of the CambrianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Hou and Bergström 1997