Reconstructing Ancient Ecosystems

Activities to try

1. 1

   The palaeo-lab: reconstruct one mystery animal from four proxies

   Why it works: Robust reconstructions come from triangulating multiple independent proxies: each proxy answers a specific question, convergence builds justified confidence, and a conflict is a clue worth investigating.

   1. Work through a multi-station lab investigating a single mystery animal: (1) section a leg bone and count the growth rings to estimate age-at-death and whether it was still growing fast when it died; (2) read a tooth's isotope trace along the crown — a seasonal rhythm in oxygen (δ18O) records seasonal changes in drinking water and climate, which even an animal that never moves will show; movement between regions (migration) is suggested only when values shift away from the local baseline, ideally checked with another tracer such as strontium; carbon (δ13C) indicates diet type (e.g. C4 grassland grazing vs C3 browsing where C4 grasses existed, or open vs closed-canopy feeding); (3) examine a coprolite linked to the animal (by size, shape and where it was found, which is itself an inference) and identify plant or bone fragments to establish diet; (4) identify a fossil leaf assemblage to reconstruct habitat and climate.
   2. Record a distinct inference from each station rather than one overall guess.
   3. Combine the separate results into a single ecosystem reconstruction (diet, age/growth, seasonal movement, habitat), stating which evidence supports each claim.
   4. Encounter a built-in case where two proxies appear to conflict, and decide how to interpret the clash (e.g. a genuine dietary change over the animal's life, seasonal variation, or reworked material) rather than discarding one result.
   5. Rate which conclusions are strongest and explain why — those where independent lines converge are more reliable than those resting on a single ambiguous source. Treat each proxy's answer as a constrained estimate with uncertainty, not an exact value.
2. 2

   Match the proxy to the inference

   Why it works: Knowing which method answers which question, and why multiple lines beat a single source, underpins being able to perform the synthesis.

   1. Match each proxy to the inference it supports: growth rings ↔ age and growth rate; tooth δ18O ↔ seasonal climate/water source (possible migration only if values depart from the local baseline); tooth δ18O ↔ diet type is wrong, so pair tooth δ13C ↔ diet type; coprolite contents ↔ diet; fossil plant assemblage ↔ habitat/climate.
   2. Sequence the analysis workflow for investigating a specimen.
   3. Answer why combining several independent lines is stronger than relying on one.
3. 3

   Guided tour of a reconstructed ecosystem scene

   Why it works: Many facts about a vanished ecosystem are established by specific analytical methods, not by bones alone.

   1. Explore an annotated reconstructed-ecosystem scene with tap-to-reveal 'how we know' tags: tapping an animal or plant reveals which proxy and analysis established each fact.
   2. After exploring, name two kinds of evidence beyond bones and what each tells you, then explain how growth rings or tooth isotopes are read for one specific inference.