Ichthyostega

Ichthyostega, from Ancient Greek ἰχθύς (ikthús), meaning "fish", and στέγη (stégē), meaning "roof", is an extinct genus of limbed tetrapodomorphs from the Late Devonian of what is now Greenland. It was among the earliest four-limbed vertebrates ever in the fossil record and was one of the first with weight-bearing adaptations for terrestrial locomotion. Ichthyostega possessed lungs and limbs that helped it navigate through shallow water in swamps. Although Ichthyostega is often labelled a 'tetrapod' because of its limbs and fingers, it evolved long before true crown group tetrapods and could more accurately be referred to as a stegocephalian or stem tetrapod. Likewise, while undoubtedly of amphibian build and habit, it is not a true member of the group in the narrow sense, as the first modern amphibians appeared in the Triassic Period. Until finds of other early stegocephalians and closely related fishes in the late 20th century, Ichthyostega stood alone as a transitional fossil between fish and tetrapods, combining fish and tetrapod features. Newer research has shown that it had an unusual anatomy, functioning more akin to a seal than a salamander, as previously assumed.

Ichthyostega

OlegTarabanov · CC BY-SA 3.0 · 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
IchthyostegidaePBDB
Motility
actively mobilePBDB, for Osteichthyes
Length
1.5 mWikidata

Time the record covers

At most 14 million years on record.

Every occurrence read is dated to somewhere between 372.15 Mya and 358.86 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.

Devonian — about 6 of 6 occurrencesDevonianCarboniferous — about 0 of 6 occurrences372–372 Mya — about 0.2 occurrences372–371 Mya — about 0.2 occurrences371–371 Mya — about 0.2 occurrences371–370 Mya — about 0.2 occurrences370–370 Mya — about 0.2 occurrences370–369 Mya — about 0.2 occurrences369–369 Mya — about 0.2 occurrences369–368 Mya — about 0.2 occurrences368–368 Mya — about 0.2 occurrences368–367 Mya — about 0.2 occurrences367–367 Mya — about 0.2 occurrences367–366 Mya — about 0.2 occurrences366–366 Mya — about 0.2 occurrences366–366 Mya — about 0.2 occurrences366–365 Mya — about 0.2 occurrences365–365 Mya — about 0.3 occurrences365–364 Mya — about 0.3 occurrences364–364 Mya — about 0.3 occurrences364–363 Mya — about 0.3 occurrences363–363 Mya — about 0.3 occurrences363–362 Mya — about 0.3 occurrences362–362 Mya — about 0.3 occurrences362–361 Mya — about 0.3 occurrences361–361 Mya — about 0.3 occurrences361–360 Mya — about 0.3 occurrences360–360 Mya — about 0.3 occurrences360–359 Mya — about 0.3 occurrences359–359 Mya — about 0.2 occurrences372.6 Mya358.4 Mya

6 occurrences of Ichthyostega on record, most of them in the Devonian. 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

6 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

2 formations

Britta Dal — 73.50°N, 23.17°WEvieux — 50.45°N, 5.06°E

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The named rock units Ichthyostega has been recovered from, largest first. Drawn where the rock is now, not where it formed. 4 occurrences have no formation on record, which is common for older literature.

Ichthyostega and its relatives

Devonian

Where Ichthyostega and its relatives were recorded in the Devonian.

Found in the same rock

14 taxa

The Paleobiology Database records 2 sites for Ichthyostega, and this reads all of them. The number is how many of those sites it was catalogued from too.

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

3 references

Each of the 6 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 Ichthyostega

Credit
OlegTarabanov
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

No 3D scan of Ichthyostega was found in Smithsonian Open Access and Sketchfab.

MorphoSource 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 itIchthyostegidae through timeFormations of the DevonianThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Säve-Söderbergh 1932