Dinosaurs, chickens, and evolution | Dana Jones Rashid | TEDxBozeman

Summary — scientific concepts, discoveries and phenomena

Definition of evolution

Evolution = heritable (usually genetic) change in living things that affects adaptation and survival.

Evolution operates on multiple timescales, from very short (minutes–months; e.g., cancer, bacterial antibiotic resistance) to very long (millions–billions of years; cumulative genetic change over deep time).

Subject of study

• Long-term evolution of birds from Mesozoic (non-avian) dinosaurs.
• Focused case: evolution of the bird tail from long, reptilian-like tails to the short tail with a fused terminal bone (the pygostyle) found in modern birds.

Fossil record and timing

• Early birds such as Archaeopteryx possessed long tails.
• Around ~130 million years ago there is an abrupt appearance of short-tailed birds.
• Long- and short-tailed forms coexisted for a couple million years, after which all modern birds share the shorter, fused-tail (pygostyle) configuration.
• No Cretaceous fossil intermediate has been found that shows a short tail without pygostyle fusion.

Evo‑devo approach (methodology)

The research combines paleontology with developmental biology and genetics to infer mechanisms behind deep-time changes:

• Use of modern bird (chicken) DNA, other vertebrate genomes, and embryonic development patterns.
• Comparison of embryonic tail development (e.g., chicken) with genetic mutant phenotypes in model organisms (e.g., mouse mutants).
• Integrating “what and when” from fossils with “how” from developmental genetics.

Key discovery / hypothesis from the DinoChicken Project

• Changes in somites (embryonic precursors of vertebrae) at the end of the tail can account for both tail shortening and vertebral fusion seen in modern birds.
• Mouse mutants that exhibit similar somite/end-tail changes also show short, fused tails and altered spinal nerve formation — matching features observed in bird tails.
• This points to a relatively simple genetic/developmental change (potentially a single mutation or a small set of changes) as a plausible explanation for the abrupt morphological shift in the fossil record.

Broader implications and examples

• Single or few genetic changes can produce large morphological effects (examples: some forms of human dwarfism; much dog-breed diversity traced to a small number of genes).
• Medical relevance: vertebral fusion seen in bird tails resembles the human disease ankylosing spondylitis; chickens could serve as a novel model to study vertebral fusion.
• Evo‑devo strengthens interpretation of fossils by connecting genotype → developmental process → phenotype.

Scientific perspective

Science advances by proposing hypotheses, testing them, and remaining open to surprising results. Cross-disciplinary approaches (paleontology + developmental genetics) are unlocking explanations for deep‑time evolutionary events.

Researchers / sources featured

• Dana Jones Rashid — evolutionary biologist; speaker; involved in the DinoChicken Project
• Jack Horner — paleontologist; collaborator and inspiration for the DinoChicken Project
• DinoChicken Project — research program studying dinosaur → bird (chicken) evolution
• Archaeopteryx — early bird fossil cited as a reference point
• Mouse mutants and chicken embryos — model systems used in the work
• Jurassic Park (movies) — cited as an inspirational source

Translator: Rhonda Jacobs Reviewer: Ellen Maloney