Every age on this page is answered by fossils alone: the rock database we use for the wider region does not reach Britain, so it has nothing to add here. Of the 2,299 fossils recorded around this town, 1,275 — about 55 in every 100 — sit at a single age, around 100 million years ago. At 100 and 200 million years ago a few land animals appear among the sea creatures. One age on this page has neither witness at all, and the page says so rather than filling the gap.
The answer, age by age
Five ages in the past of this place, each one a window rather than a day. Each says which witness spoke — and where our evidence cannot answer yet, it says that too.
“Ma” means millions of years ago. The dashed mark means our sources have nothing for that age — which is a finding, not a fault.
One age, more than half the fossils
The loud age — around 100 million years ago
2,046 fossils near this town have an age range containing this moment (1902 from the sea, 143 from land among the ones shown). Nothing corroborates them at the regional scale: the rock database has no column here.
The quiet age — around 250 million years ago
No fossil near this town has an age range containing this moment, so the local witness has nothing to say here.
The land animals in the middle
At 100 and 200 million years ago the fossils near this town are not all sea creatures: a few land animals are recorded among them, and they are a tiny minority of what has been found.
One age holding 1,275 of the 2,299 fossils here is worth stopping on, and it is easy to read the wrong way. It does not mean more was alive then. It means more has been FOUND and RECORDED from then — the rock of that age is at the surface where people have dug, and the ages either side are not.
That is a fact about collecting, not about the past. It is also the reason this page never counts fossils to decide what a place was like: the pile tells you where people have looked. Working out what the animals themselves mean is a different job, and a harder one.
Travel back in time
The plate model can place this ground at every age on this page, and it puts it a very long way south of where it is now. Watch the latitude climb as the rows come forward in time.
250
million years agojump to the evidence250 million years ago, the plate model puts this ground about 13° north of the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 6.4° of latitude apart, which is several hundred kilometres. Treat it as one model's answer, not a photograph.
200
million years agojump to the evidence200 million years ago, the plate model puts this ground about 18° north of the equator. Published models disagree by about 4.4° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
150
million years agojump to the evidence150 million years ago, the plate model puts this ground about 23° north of the equator. Published models disagree by about 4.3° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
100
million years agojump to the evidence100 million years ago, the plate model puts this ground about 33° north of the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 5.3° of latitude apart, which is several hundred kilometres. Treat it as one model's answer, not a photograph.
66
million years agojump to the evidence66 million years ago, the plate model puts this ground about 44° north of the equator. Published models disagree by about 3.7° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
What was the water doing?
Five ages, oldest first. Each one has two kinds of witness — the rock of the wider region, and the fossils dug up near the town — and they are kept apart on purpose, because they are answers to different questions.
Each age here is a marker on the timeline, not a single day. The evidence that belongs to it comes with an age range of its own that overlaps the marker — so it can tell you what this stretch of time was like, and never what was happening on one exact date.
Our evidence has no witness here
Around 250 million years ago
250 million years ago, the plate model puts this ground about 13° north of the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 6.4° of latitude apart, which is several hundred kilometres. Treat it as one model's answer, not a photograph.
An open question
Neither of the evidence sources we use can answer this one: the regional rock database does not cover this place at all, so it has nothing to say about 250 million years ago, and no fossil dug up nearby covers that age either. That is a real gap in the evidence, not a gap in the past — and saying so is more useful than guessing.
Only the fossils speak
Around 200 million years ago
200 million years ago, the plate model puts this ground about 18° north of the equator. Published models disagree by about 4.4° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
The rock of the region
The regional rock record does not cover this place at all, so there is no regional answer for 200 million years ago.
The fossils dug up nearby
19 fossils dug up near Brighton have an age range covering 200 million years ago: 16 from the sea, 3 from land. The closest of them was found about 14 km away — near the town, never under it.
Only the fossils speak
Around 150 million years ago
150 million years ago, the plate model puts this ground about 23° north of the equator. Published models disagree by about 4.3° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
The rock of the region
The regional rock record does not cover this place at all, so there is no regional answer for 150 million years ago.
The fossils dug up nearby
16 fossils dug up near Brighton have an age range covering 150 million years ago: 16 from the sea, 0 from land. The closest of them was found about 47 km away — near the town, never under it.
Only the fossils speak
Around 100 million years ago
100 million years ago, the plate model puts this ground about 33° north of the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 5.3° of latitude apart, which is several hundred kilometres. Treat it as one model's answer, not a photograph.
The rock of the region
The regional rock record does not cover this place at all, so there is no regional answer for 100 million years ago.
The fossils dug up nearby
1275 fossils dug up near Brighton have an age range covering 100 million years ago: 1271 from the sea, 3 from land, 1 that nobody has classified. The closest of them was found about 1.5 km away — near the town, never under it.
Only the fossils speak
Around 66 million years ago
66 million years ago, the plate model puts this ground about 44° north of the equator. Published models disagree by about 3.7° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
The rock of the region
The regional rock record does not cover this place at all, so there is no regional answer for 66 million years ago.
The fossils dug up nearby
46 fossils dug up near Brighton have an age range covering 66 million years ago: 45 from the sea, 0 from land, 1 that nobody has classified. The closest of them was found about 9.8 km away — near the town, never under it.
What was dug up nearby?
Every fossil below was dug up somewhere around Brighton, never underneath it, so each carries the distance to where it was actually found. The ages are not evenly served: one of them holds more finds than all the others together, and the list below shows why that is a fact about digging rather than about the past.
Around 66 million years ago
A Cretirhynchia (Lewesirhynchia) exsculpta from around this time (its own age range is 72.2–83.6 million years) was dug up about 5.3 km from here, in the Upper Chalk, East Sussex.
A Cretirhynchia (Lewesirhynchia) exsculpta from around this time (its own age range is 72.2–83.6 million years) was dug up about 7.0 km from here.
A Cretirhynchia (Lewesirhynchia) exsculpta from around this time (its own age range is 72.2–83.6 million years) was dug up about 7.3 km from here.
Around 100 million years ago
A Lophiostomus dixoni from 100 million years ago was dug up about 1.5 km from here, in Brighton and Hove.
A Rhagasostoma minuens from around this time (its own age range is 83.6–85.7 million years) was dug up about 2.5 km from here, in East Sussex.
A Hoplopteryx simus from around this time (its own age range is 85.7–93.9 million years) was dug up about 3.2 km from here, in West Sussex.
Around 150 million years ago
An Eusuchia from around this time (its own age range is 132.6–143.1 million years) was dug up about 15 km from here, in East Sussex.
A fossil the database can only call “Ornithischia” from around this time (its own age range is 125.77–132.6 million years) was dug up about 15 km from here, in the Weald Clay.
A Bernissartia from around this time (its own age range is 125.77–132.6 million years) was dug up about 15 km from here, in the Weald Clay.
Around 200 million years ago
A Hirmeriella muensteri from 200 million years ago was dug up about 14 km from here.
An Equisetites from 200 million years ago was dug up about 14 km from here.
A Classopollis from 200 million years ago was dug up about 14 km from here.
We show these places to the nearest few kilometres rather than pinning them exactly. The scientists who recorded them know the spot far better than that — the full record is one click away in the Paleobiology Database, and it is free for anyone to read. We round them here because a map made for children is not a map for digging things up, not because anything is being hidden.
What changed?
This ground has travelled. The plate model places it deep in the northern tropics at the oldest age on this page and at its present latitude today — the whole width of the subtropics, carried by the plate it sits on.
The rock at the surface today is younger than all of it. The geological map of this exact point returns Mesozoic sedimentary rocks (Late Cretaceous), Late Cretaceous limestone (Late Cretaceous), White Chalk Subgroup (Late Cretaceous).
This page says nothing about how the chalk under this town was made, or how the cliffs got their shape. We have no source for either, so we do not guess.
Try it yourself
The sea animals in this record were dug up around this town, each a recorded distance away — never underneath it. They swam in water, and that water is still here, still going round. Some of it comes out of the taps in this town today.
Every age on this page is answered by one witness only: the fossils. The rock database we use for the wider region does not cover Britain, so it cannot agree or disagree with them. One witness is still evidence — it is just evidence that nothing has checked.
If almost all the fossils come from one age, does that mean more animals were alive then — or that we have looked harder at that rock?
How sure are we?
Column facts describe an area of thousands to tens of thousands of km², centred tens of kilometres from the town coordinate. They are claims about a region, never about the rock beneath the town.
Fossil facts are a bounding-box sample around the town, each with its own distance from it; a fossil is never "here". The absence of fossils is not evidence of the absence of life — only of the absence of a recorded, published dig in this box.
Positions are model outputs, not observations. Independent plate models disagree by hundreds of kilometres at these ages, and that spread is the honest size of the uncertainty.
The land/sea question is answered only by the regional rock and the local fossils, separately, and never by the reconstruction — which says where this ground was and cannot say whether it was wet. There is deliberately no single field holding a one-word answer, because answering in one word would require merging a regional claim with a local one (CLAUDE.md rule 5). The nearby fossils are reported as a census of what has been found — which kinds are present, and how many of each — and never counted into a verdict: occurrence records are not statistically equivalent observations, so a plurality of them cannot establish an environment (science review, 2026-08-30).
Fossils are binned to their nearest slice age by age-range midpoint, with boundaries at the inter-slice midpoints 83, 125, 175 and 225 Ma. Those boundaries are an editorial choice, not a published stratigraphic scheme; a reviewer may prefer stage boundaries. Every occurrence keeps its own age range so the choice can be re-examined.
Sources
Macrostrat — the rock of the regionRead from version 2.3.9 of its data service on 30 August 2026.Peters, S.E. et al. Macrostrat: a platform for geological data integration and deep-time research. https://macrostrat.org, accessed on (date)Palaeogeography: Wright, N., Zahirovic, S., Müller, R. D., and Seton, M. Towards community-driven paleogeographic reconstructions: integrating open-access paleogeographic and paleobiology data with plate tectonics. Biogeosciences 10:1529-1541
The Paleobiology Database — the fossils dug up nearbyPBDB publishes no dataset version string; the data-service path (data1.2) and the datainfo access_time bound this claim.Fossil occurrence data from the Paleobiology Database (https://paleobiodb.org), released under CC0 1.0.Palaeo-coordinate cross-check (Paleobiology Database `pgm=gplates`): Wright et. al., 2013; Towards community-driven paleogeographic reconstructions.Palaeo-coordinate cross-check (Paleobiology Database `pgm=scotese`): Scotese, C.R., 2021. An Atlas of Paleogeographic Maps: The Seas Come In and the Seas Go Out, Annual Reviews of Earth and Planetary Sciences, v. 49, p. 669-718.Palaeo-coordinate cross-check (Paleobiology Database `pgm=seton`): Seton et. al., 2012; Global continental and ocean basin reconstructions since 200 Ma.
The EarthByte plate model — where this ground used to beMULLER2019 version 3.0, run with pyGPlates 1.0.0, licensed CC BY 4.0.GPlates: Müller, R. D., Cannon, J., Qin, X., Watson, R. J., Gurnis, M., Williams, S., Pfaffelmoser, T., Seton, M., Russell, S. H. J., Zahirovic S. (2018). GPlates: Building a virtual Earth through deep time. Geochemistry, Geophysics, Geosystems, 19, 2243-2261. https://doi.org/10.1029/2018GC007584Reconstructions computed with the GPlates Web Service (EarthByte Group, The University of Sydney).Plate model: Müller, R. D., Zahirovic, S., Williams, S. E., Cannon, J., Seton, M., Bower, D. J., Tetley, M. G., Heine, C., Le Breton, E., Liu, S., Russell, S. H. J., Yang, T., Leonard, J., and Gurnis, M. (2019), A global plate model including lithospheric deformation along major rifts and orogens since the Triassic. Tectonics, vol. 38, https://doi.org/10.1029/2018TC005462. Licensed CC BY 4.0.Plate model: Zahirovic, S., Eleish, A., Doss, S., Pall, J., Cannon, J., Pistone, M., Tetley, M. G., Young, A., & Fox, P. (2022). Subduction kinematics and carbonate platform interactions. Geoscience Data Journal, 9(2), p.371-383. Licensed CC BY 4.0.Coastline and static-polygon data by the EarthByte Group, licensed CC BY 3.0 Unported.
This record was assembled on from the datasets above. The ancient positions are reconstructions from a published plate model, not observations.