Cambrian
Hallucigenia
Real size: 0.5 to 5 cm
A tiny spiny worm. Scientists first drew it upside down, spines as legs.
In game: Hatched from a complete Cambrian set; first egg took about 5 minutes.
Prehistoric Farm Fossils & Animals by Period
Dig islands and what unlocks them
| Period | Island | Shovel needed | Animals seen dug up |
|---|---|---|---|
| Cambrian | Cambrian Island | Starter shovel | Hallucigenia, Pikaia, Opabinia, Trilobite |
| Devonian | Devonian Island | Bronze shovel (2,500 coins) | Tiktaalik, Ichthyostega |
| Triassic | Triassic Island | Not shown yet | Not shown yet |
| Jurassic | Jurassic Island | Better than starter (game says 'I need a better shovel') | Sauropod skeleton, Small theropods |
| Cretaceous | Cretaceous (island not shown in footage) | Not shown yet | Not shown yet |
| Cretaceous Seas | The open sea and Sunken Grotto | Sea content, not a dig island | Mosasaurus (boss) |
Period names come from the game's fossil collection menu. The animals listed are the ones seen dug up in recorded play (Jurassic Dinoz, Oct 2026). Real-world dates are the ICS geologic time scale; sizes are typical published estimates.
"Not shown yet" means none of our sources has footage of that island's digs. We would rather leave a gap than guess. The shovel-to-island rule itself is solid: the starter shovel digs Cambrian only, and later islands answer "I need a better shovel".
The animals, and the real fossils behind them
Cambrian
Pikaia
Real size: about 4 cm
One of the earliest known chordates, a distant relative of every animal with a backbone.
In game: Common Cambrian dig find.
Cambrian
Opabinia
Real size: about 7 cm
Five eyes on stalks and a long grabbing nozzle in front of its mouth.
In game: Cambrian dig find.
Cambrian
Trilobite
Real size: 1 to 70 cm (most under 10)
Armored sea arthropods that lasted almost 300 million years.
In game: The most frequent Cambrian fossil in the footage.
Devonian
Tiktaalik
Real size: up to about 2.7 m
A 375-million-year-old fish with a neck and wrist bones, half fish, half land animal.
In game: Built from Devonian fossils; its egg hatched in 2:30.
Devonian
Ichthyostega
Real size: about 1.5 m
One of the first animals with four legs and toes, still living mostly in water.
In game: Devonian dig find.
Cretaceous Seas
Mosasaurus
Real size: up to about 12 m
A giant sea lizard, related to monitor lizards and snakes rather than dinosaurs.
In game: Open-sea boss. Players team up and take it down with spears.
Each period in one paragraph
Cambrian 538.8 to 485.4 million years ago
The Cambrian explosion: most animal groups first show up in the fossil record here, in shallow seas. Nothing lived on land yet.
In Prehistoric Farm: Cambrian Island. Reach: Starter boat, under a minute from spawn. Set size: 6 pieces in the collection menu.
Devonian 419.2 to 358.9 million years ago
The age of fishes. Lobe-finned fish like Tiktaalik start using their fins as legs, and the first four-limbed animals appear.
In Prehistoric Farm: Devonian Island. Reach: Starter boat. Set size: Not counted on screen.
Triassic 251.9 to 201.4 million years ago
After the biggest mass extinction on record, the first dinosaurs, pterosaurs and mammals appear.
In Prehistoric Farm: Triassic Island. Reach: Seen on the way out with the starter boat. Set size: Not shown yet.
Jurassic 201.4 to 145 million years ago
Giant long-necked sauropods and the first birds. Pangaea is splitting apart.
In Prehistoric Farm: Jurassic Island. Reach: Starter boat can sail there. Set size: Not shown yet.
Cretaceous 145 to 66 million years ago
Tyrannosaurus, Triceratops and the first flowering plants. It ends with the asteroid impact 66 million years ago.
In Prehistoric Farm: Cretaceous (island not shown in footage). Reach: Not shown yet. Set size: Not shown yet.
Cretaceous Seas Late Cretaceous, about 82 to 66 million years ago
Mosasaurs were marine lizards up to about 12 m (40 ft) long that ruled the late Cretaceous oceans. They were not dinosaurs.
In Prehistoric Farm: The open sea and Sunken Grotto. Reach: Boat or the Aquatic Dinosaur from SORRYFORDELAYS. Set size: Sea reptile eggs are stolen from the Grotto.
How a set becomes a dinosaur
- Dig on the island until the collection menu shows the set complete ("Ready to extract DNA").
- Take the set to the fossil station. DNA cannot be extracted at the dig site.
- Trade at Dr. Ivy's DNA Lab for an egg, then incubate it. Full steps: eggs and raising.
Fossil list checked:
Fossil Questions
How many fossil periods are there?
Six, as listed in the fossil collection menu: Cambrian, Devonian, Triassic, Jurassic, Cretaceous and Cretaceous Seas.
How many fossils make a set?
The Cambrian collection showed 6 pieces in recorded play, and the set was "ready to extract DNA" once complete. Other periods were not counted on screen.
Which animal is easiest to get first?
A Cambrian animal. Hallucigenia was the first hatch in our source footage, from the island under a minute from spawn.
Are these real animals?
Yes. Hallucigenia, Pikaia, Opabinia, trilobites, Tiktaalik, Ichthyostega and Mosasaurus are all known from real fossils. The facts on this page come from the published fossil record, not from the game.