Niche partitioning shaped herbivore macroevolution through the early Mesozoic.

Area of Science:

• Paleontology
• Ecology
• Evolutionary Biology

Background:

• The Triassic period (252–201 million years ago) saw ecosystems recovering from the Permian-Triassic mass extinction.
• Herbivory evolved multiple times, with various reptile groups rising and falling.
• Dinosaur ascendancy was previously attributed to competitive replacement or opportunistic advantage after extinctions.

Observation:

• This study analyzes herbivore functional morphology and ecology across the Triassic and Early Jurassic.
• Five distinct herbivore feeding guilds were identified: ingestion generalists, prehension specialists, durophagous specialists, shearing pulpers, and heavy oral processors.
• Herbivore clades largely minimized competition by specializing in different guilds.

Findings:

• Ecosystems underwent significant restructuring multiple times due to environmental pressures.
• Previously dominant herbivore groups were displaced by newly evolving forms.
• Dinosaur dominance resulted from a combination of post-extinction opportunities and inherent competitive advantages.

Implications:

• Understanding herbivore guild dynamics provides insight into Mesozoic ecosystem structure.
• The study refines theories on dinosaur ascendancy, highlighting niche partitioning and environmental contingency.
• This research contributes to reconstructing past biodiversity and ecological interactions.