Romer's gap

−360 —

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−355 —

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−350 —

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−345 —

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−340 —

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−335 —

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−330 —

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−325 —

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−320 —

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−315 —

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−310 —

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−305 —

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−295 —

Permian

Devonian

C
a
r
b
o
n
i
f
e
r
o
u
s

M
i
s
s
i
s
s
i
p
p
i
a
n

P
e
n
n
-
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a
n

R
o
m
e
r
'
s

G
a
p

9

10

15

14

13

12

1

2

3

7

8

11

6

16

17

18

19

4

5

Paleozoic

Axis scale: millions of years ago.

Known fossil ranges.
Ghost lineages.

1: "Anthracosauria" 2: Temnospondyli 3: "Microsauria" 4: Seymouriamorpha 5: Diadectidae 6: Nectridea 7: Aistopoda 8: Amniota 9: Baphetidae 10: Colosteidae 11: Gephyrostegidae 12: Casineria 13: Crassigyrinus 14: Whatcheeriidae 15: Adelogyrinidae 16: Ventastega 17: Ichthyostega 18: Acanthostega 19: Tulerpeton

References: Smithson et al. (2012)

Romer's gap is an apparent gap in the Paleozoic tetrapod fossil record noted in the studies of paleontology and evolutionary biology, which represent periods in the Early Carboniferous from which excavators have not yet found relevant transitional fossils. It is named after American paleontologist Alfred Romer, who first recognised it in 1956. Studies published in 2016 and 2025 describing discoveries in Scotland and Australia began to close this gap in palaeontological knowledge.