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[dinosaur] Mirusavis, new enantiornithine bird from Early Cretaceous of China (free pdf)

Ben Creisler

A new paper not yet mentioned:

Free pdf:

Mirusavis parvus, gen. et. sp. nov.

Min Wang, Jingmai K OâConnor, Alida M Bailleul & Zhiheng Li (2019)
Evolution and distribution of medullary bone: evidence from a new Early Cretaceous enantiornithine bird.
National Science Review, nwz214 (advance online publication)
doi: https://doi.org/10.1093/nsr/nwz214

Living birds are unique among vertebrates in the formation of a female-specific bone tissue called medullary bone (MB) that is strictly associated with reproductive activity. MB is a rapidly mobilized source of calcium and phosphorus for the production of eggshell. Among living taxa, its skeletal distribution can be highly extensive such that it even exists in the ribs of some species. Due to its ephemeral nature MB is rarely fossilized, little is understood with regards to the origin of MB and its skeletal distribution in early taxa. Here we describe a new Early Cretaceous enantiornithine bird, Mirusavis parvus, gen. et. sp. nov., indicating that skeleton-wide distribution of MB appeared early in avian evolution. We suggest that this represents the plesiomorphic condition for the Aves, and that the distribution of MB observed among extant neornithines is a product of increased pneumatization in this lineage and natural selection for more efficient distribution of MB.