A state is not a point, and this page is standing on one: a box around Fort Worth. Inside it are 1,552 recorded fossils, and 1,550 of them belong to a single age around 100 million years ago — the other four ages between them hold three. 4 of the five have no witness at all, and this page leaves those blank rather than reaching sideways for something to say. The interesting number is a smaller one: 33 of these fossils are recorded as marine AND as living on land, — the database that holds them will not force a delta into one box, and neither will this page.
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.
The fossils that are both
Every other page on this site sorts its fossils into two piles: creatures the database records as living in the sea, and creatures it records as living on land. This record would not sort. 33 of its occurrences come back from the database as both at once.
Deltasuchus motherali
Found about 24.3 km away · 100.5–93.9 million years old · from a single rock unit
The environment the database records for it is a delta plain.
A delta is where a river arrives at the sea and drops what it has been carrying. It is not the land and it is not the ocean; it is the argument between them, and it moves. A database asked to file a delta as one or the other has to lose something either way, so this one hands back both answers and lets whoever is reading decide what to do about it.
This page does nothing about it. The counts above keep those fossils in a category of their own, the question at the top of the page is not answered for them, and no sentence here quietly rounds them into the sea to suit this page's own subject.
Until this record was built, no page on this site had met one. The check that noticed them had been running since the fossil database was first wired in and had never once fired.
Travel back in time
Four of the five rows below are empty, and one is not. Almost everything this record knows sits in a single band of time, which is a fact about where people have dug rather than about how long anything lasted.
250
million years agojump to the evidence250 million years ago, the plate model puts this ground almost on the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 5.4° 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 almost on the equator. Published models agree more closely here, within about 2.8° of latitude, but it is still one model's answer rather than a photograph.
150
million years agojump to the evidence150 million years ago, the plate model puts this ground about 15° north of the equator. Published models disagree by about 4.5° 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 28° 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.
66
million years agojump to the evidence66 million years ago, the plate model puts this ground about 35° north of the equator. Published models agree more closely here, within about 1.8° of latitude, but it is still one model's answer rather than 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 city — 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 almost on the equator. This is one of the ages the models argue about most: published reconstructions put it as much as 5.4° 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: our regional rock record holds no unit for 250 million years ago at this point, 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.
Our evidence has no witness here
Around 200 million years ago
200 million years ago, the plate model puts this ground almost on the equator. Published models agree more closely here, within about 2.8° of latitude, but it is still one model's answer rather than a photograph.
An open question
Neither of the evidence sources we use can answer this one: our regional rock record holds no unit for 200 million years ago at this point, 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.
Our evidence has no witness here
Around 150 million years ago
150 million years ago, the plate model puts this ground about 15° north of the equator. Published models disagree by about 4.5° of latitude here — a few hundred kilometres — so it is one model's answer, not a photograph.
An open question
Neither of the evidence sources we use can answer this one: our regional rock record holds no unit for 150 million years ago at this point, 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.
The rock of the region says sea
Around 100 million years ago
100 million years ago, the plate model puts this ground about 28° 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
Across the wider region, the rock from 100 million years ago — the Washita Gp — was laid down in the sea. That is a statement about roughly 21,100 square kilometres of region, centred about 84 km from the city — not about the ground under one street.
The fossils dug up nearby
999 fossils dug up near Fort Worth have an age range covering 100 million years ago: 939 from the sea, 27 from land. The closest of them was found about 2.8 km away — near the city, never under it.
The regional column spanning 100 Ma is marine; the fossils dug up near this place whose age range contains 100 Ma are 939 marine, 27 terrestrial and 0 unclassified. These are different claims about different things — a region tens of thousands of km² wide, and individual digs kilometres away — and both are shown. The nearby fossil record is mixed — it holds both sea animals and land animals whose age ranges overlap this age.
Our evidence has no witness here
Around 66 million years ago
66 million years ago, the plate model puts this ground about 35° north of the equator. Published models agree more closely here, within about 1.8° of latitude, but it is still one model's answer rather than a photograph.
An open question
Neither of the evidence sources we use can answer this one: our regional rock record holds no unit for 66 million years ago at this point, 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.
What was dug up nearby?
These were dug up around Fort Worth and never underneath it, so each carries the distance to where it was actually found. Watch the environment column: some of these creatures are filed under land and sea together, and that column is the database speaking, not this page.
Around 66 million years ago
A Protostegidae from around this time (its own age range is 72.2–89.8 million years) was dug up about 42 km from here, in the Austin Chalk, Dallas County.
Around 100 million years ago
A Deltasuchus motherali from 100 million years ago was dug up about 24 km from here, in the Lewisville, Tarrant County.
An Anisoceras armatum from around this time (its own age range is 100.5–106.3 million years) was dug up about 1.0 km from here, in the Weno, Tarrant County.
A Nodosauridae from around this time (its own age range is 100.5–106.3 million years) was dug up about 2.8 km from here, in the Paw Paw, Tarrant County.
A Crateraster texensis from around this time (its own age range is 100.5–106.3 million years) was dug up about 2.8 km from here, in the Weno, Fort Worth County.
Around 150 million years ago
A Latheticocarcinus pikeae from around this time (its own age range is 125.77–143.1 million years) was dug up about 51 km from here, in Denton County.
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?
The plate model puts this ground much further south at the older ages and brings it north through the page. A position is where a piece of the surface was, and says nothing about what was on top of it.
The rock at the surface today is younger than all of it. The geological map of this exact point returns Mesozoic sedimentary rocks (Mesozoic), Early Cretaceous sedimentary (Cretaceous), Fort Worth Limestone and Duck Creek Formation, undivided (Albian).
Nothing here describes Texas. It describes a box about a hundred kilometres across with Fort Worth in the middle, and a state is very much larger than that.
Try it yourself
A delta is a place you can still visit — any river mouth will do. Stand where the fresh water meets the salt and try to draw the line.
This is the page for what happens when the real world will not fit the boxes we made for it. The right response to a thing that is both is not to pick one; it is to say it is both and keep going.
If a creature lived where a river met the sea, is it a sea creature? Who decides — and what do you lose whichever way you answer?
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 2 September 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.
