Related Experiment Video
Updated: Feb 13, 2026

Visually Sexing Loggerhead Shrike Lanius Ludovicianus Using Plumage Coloration and Pattern
Published on: March 8, 2020
A diminutive perinate European Enantiornithes reveals an asynchronous ossification pattern in early birds
Fabien Knoll1,2, Luis M Chiappe3, Sophie Sanchez4,5
1ARAID-Fundación Conjunto Paleontológico de Teruel-Dinopolis, 44002, Teruel, Spain. knoll@fundaciondinopolis.org.
Abstract:
Fossils of juvenile Mesozoic birds provide insight into the early evolution of avian development, however such fossils are rare. The analysis of the ossification sequence in these early-branching birds has the potential to address important questions about their comparative developmental biology and to help understand their morphological evolution and ecological differentiation. Here we report on an early juvenile enantiornithine specimen from the Early Cretaceous of Europe, which sheds new light on the osteogenesis in this most species-rich clade of Mesozoic birds. Consisting of a nearly complete skeleton, it is amongst the smallest known Mesozoic avian fossils representing post-hatching stages of development. Comparisons between this new specimen and other known early juvenile enantiornithines support a clade-wide asynchronous pattern of osteogenesis in the sternum and the vertebral column, and strongly indicate that the hatchlings of these phylogenetically basal birds varied greatly in size and tempo of skeletal maturation.
Related Concept Videos
Bone Formation by Intramembranous Ossification
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into ...
Bone Formation by Endochondral Ossification
Fixed Action Patterns
Patterns of Fever
Oxygen Requirements and Growth Patterns
¹H NMR Signal Multiplicity: Splitting Patterns

