Scientists compare fossilised footprint trails made by related land animals in rocks of different ages. They examine 30 trails from each age of rock.
| Age of rock in millions of years | Trails with four toe impressions | Trails with three toe impressions |
|---|---|---|
| 14 | 26 | 4 |
| 9 | 17 | 13 |
| 4 | 7 | 23 |
Which statement describes the evidence for evolution in these fossilised trails?
Both types of trail occur in the 9 million-year-old rock, showing that the populations did not change through time.
The proportion of trails with three toe impressions rises in younger rocks, showing that individual animals changed their feet as they grew.
The proportion of trails with three toe impressions rises in younger rocks, supporting change in a characteristic of related populations through time.
Three-toed trails are most common in the youngest rock, showing that the animals developed three toes because they needed them.
122 exam-style questions on OCR GCSE Biology 5.2 Natural selection and evolution, covering 5.2.1 Genetic variation within a population, 5.2.2 Developments in classification systems, 5.2.3 How evolution occurs through natural selection, 5.2.4 Evolution as change over time, 5.2.5 Evidence for evolution, and 5.2.6 Darwin and Wallace. Each one has a worked solution and a mark scheme showing where the marks go.