16 fossils. That is the whole local record for this city, all of them sea creatures and all of them at one age around 250 million years ago. 2 of the five ages have no witness of any kind, and at two more the only thing speaking is rock from the wider region, which reads dry rather than wet. Sixteen is a real number and it is a small one, and this page is careful to be worth exactly sixteen fossils.
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.
What sixteen fossils are worth
Every fossil this site can find near Las Vegas — all 16 of them — is a sea creature, and every one belongs to a single age around 250 million years ago. It is the smallest local record on the site.
A small number is not a weak version of a big one. It is a different thing, and the honest way to use it is to say what it can and cannot carry.
What it can carry
That sea creatures have been dug up near here, catalogued, and dated to that age. That is a fact about sixteen specific finds and it is solid.
What it cannot
Any claim about how long a sea was here, how deep, how far it reached, or what the other four ages were like. Sixteen finds cannot answer those and this page does not ask them to.
At 250 and 200 and 66 million years ago there is no local fossil at all, and the only witness is rock from the wider region — which reads dry rather than wet. That is printed here exactly as it would be if it read the other way round. A page that reported "the rock says sea" eagerly and "the rock says land" quietly would be teaching you which answer it preferred.
And 2 of the five ages have nothing whatever — no rock that speaks, no fossil near enough. Those rows stay blank.
Travel back in time
Only one of these rows has a local fossil in it. Two more have regional rock and nothing else, and the remainder are empty — which makes this the quietest timeline on the site.
250
million years agojump to the evidence250 million years ago, the plate model puts this ground almost on 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.
200
million years agojump to the evidence200 million years ago, the plate model puts this ground about 17° north of the equator. Published models agree more closely here, within about 2.1° 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 25° north of the equator. Published models disagree by about 4° 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 37° north of the equator. Published models agree more closely here, within about 2.5° of latitude, but it is still one model's answer rather than a photograph.
66
million years agojump to the evidence66 million years ago, the plate model puts this ground about 41° north of the equator. Published models agree more closely here, within about 0.7° 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.
The rock of the region says sea
Around 250 million years ago
250 million years ago, the plate model puts this ground almost on 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.
The rock of the region
Across the wider region, the rock from 250 million years ago — the Virgin Limestone Mbr of Moenkopi Fm — was laid down in the sea. That is a statement about roughly 17,900 square kilometres of region, centred about 38 km from the city — not about the ground under one street.
The fossils dug up nearby
No fossil dug up near here has an age range that covers 250 million years ago, so there is no local evidence for this exact age.
The rock of the region says land
Around 200 million years ago
200 million years ago, the plate model puts this ground about 17° north of the equator. Published models agree more closely here, within about 2.1° of latitude, but it is still one model's answer rather than a photograph.
The rock of the region
Across the wider region, the rock from 200 million years ago — the Moenave Fm — was laid down on land, not under the sea. That is a statement about roughly 17,900 square kilometres of region, centred about 38 km from the city — not about the ground under one street.
The fossils dug up nearby
No fossil dug up near here has an age range that covers 200 million years ago, so there is no local evidence for this exact age.
Our evidence has no witness here
Around 150 million years ago
150 million years ago, the plate model puts this ground about 25° north of the equator. Published models disagree by about 4° 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.
Our evidence has no witness here
Around 100 million years ago
100 million years ago, the plate model puts this ground about 37° north of the equator. Published models agree more closely here, within about 2.5° 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 100 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 land
Around 66 million years ago
66 million years ago, the plate model puts this ground about 41° north of the equator. Published models agree more closely here, within about 0.7° of latitude, but it is still one model's answer rather than a photograph.
The rock of the region
Across the wider region, the rock from 66 million years ago — the Unnamed — was laid down on land, not under the sea. That is a statement about roughly 17,900 square kilometres of region, centred about 38 km from the city — not about the ground under one street.
The fossils dug up nearby
No fossil dug up near here has an age range that covers 66 million years ago, so there is no local evidence for this exact age.
What was dug up nearby?
A short list, which is all there is to give. Each was dug up somewhere near the city rather than under it, and each carries the distance to where it was actually found.
Around 250 million years ago
A Leptochondria curtocardinalis from around this time (its own age range is 247–248.6 million years) was dug up about 17 km from here, in the Moenkopi (Virgin Limestone).
A Pegmavalvula triassica from around this time (its own age range is 247–248.6 million years) was dug up about 17 km from here, in the Moenkopi (Virgin Limestone).
A Neoschizodus elongatus from around this time (its own age range is 247–248.6 million years) was dug up about 17 km from here, in the Moenkopi (Virgin Limestone).
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 model places this ground at all five ages and brings it north as the rows come forward. Position is not the same as description: it says where, never what.
The rock at the surface today is younger than all of it. The geological map of this exact point returns Cenozoic sedimentary rocks (Cenozoic), Quaternary sedimentary (Cenozoic), Alluvium, undifferentiated (Cenozoic), Undivided young spring deposits (Quaternary).
Sixteen fossils is the entire local record here. Nothing on this page should be carried to the rest of Nevada, which has its own page anchored 400 km north with a different record.
Try it yourself
Sea creatures lived in water that is still going round today — including the water this very dry city now has to pipe in from a long way away.
This is the page for sample size. Sixteen is enough to say something happened and not enough to say how much, how long or how far, and telling those apart is most of what careful reading is.
If you found sixteen shells in a field, what could you honestly say about that field? What would you need before you could say more?
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.
