Microraptor with Ingested Lizard Suggests Non-specialized Digestive Function

Area of Science:

• Paleontology
• Paleoecology
• Evolutionary Biology

Background:

• Direct evidence of predator-prey relationships and diet in the fossil record is rare.
• Understanding ancient trophic interactions is crucial for reconstructing past ecosystems and behaviors.
• Microraptor zhaoianus, a volant dromaeosaurid from the Early Cretaceous Jehol Biota, is known for its asymmetrical flight feathers.

Purpose of the Study:

• To identify and describe a new lizard species found within the abdominal remains of a Microraptor specimen.
• To confirm dietary habits and predatory behavior of Microraptor.
• To analyze phylogenetic relationships of the newly discovered lizard and compare digestive strategies within Paraves.

Main Methods:

• Detailed morphological examination of the articulated lizard remains within the Microraptor fossil.
• Comparative analysis of dentition to distinguish the new species.
• Phylogenetic analysis to determine the evolutionary relationships of Indrasaurus wangi.
• Comparison of ingested prey preservation across different paravian dinosaurs.

Main Results:

• Identification of Indrasaurus wangi gen. et sp. nov., a new lizard species with unique dentition.
• Confirmation that Microraptor ingested prey whole and head-first, consistent with opportunistic predation.
• Phylogenetic analysis places Indrasaurus wangi as a basal scleroglossan, related to Liushusaurus.
• Dromaeosaurids, unlike Anchiornis, appear to have fully digested prey, suggesting digestive strategies evolved homoplastically in Paraves.

Conclusions:

• The discovery provides direct evidence of Microraptor's diet and predatory behavior.
• Indrasaurus wangi expands our understanding of Early Cretaceous lizard diversity.
• The study suggests that the evolution of pellet egestion in birds was not directly linked to the evolution of flight and occurred independently in different lineages.