Enantiornithinary

Enantiornithinary refers to the clade Enantiornithes, an extinct group of avialan dinosaurs that were widespread during the Cretaceous period. These birds are characterized by a unique skeletal feature: their scapulocoracoid is fused into a single bone, unlike modern birds which have separate scapula and coracoid. This fusion is a distinguishing feature of the group, setting them apart from other bird lineages. Enantiornithes are known from fossil evidence found on all seven continents, indicating a global distribution.

Fossil discoveries have revealed a remarkable diversity within Enantiornithes, with over 100 described species. These birds varied in size, from small, sparrow-sized individuals to larger forms comparable to modern crows. Their diets also differed, with evidence suggesting some were insectivores, while others were piscivores or frugivores. Many enantiornithes possessed well-developed teeth, a trait lost in most modern birds. Their plumage is known from exceptionally preserved fossils, showing sophisticated feather structures including iridescent feathers in some species.

The reproductive biology of enantiornithes is also illuminated by fossils. Nests containing eggs and even hatchlings have been found, providing insights into their nesting behaviors and parental care. Evidence suggests that some enantiornithes were altricial, meaning their young hatched helpless and required extensive care. The widespread presence and diversity of Enantiornithes highlight their ecological success throughout the Cretaceous. Despite their abundance, they did not survive the Cretaceous-Paleogene extinction event, which marked the end of the non-avian dinosaurs. The exact reasons for their extinction are debated, but it is generally accepted that the environmental catastrophic impact of the asteroid likely played a significant role.