First find of fossil bird with unlaid egg
A partial bird fossil with feather impressions (see photo) has been found in supposed 110-million-year-old deposits in China. Amazingly, this enantiornithine bird (an extinct type, also called ‘opposite bird’), also had remains of its egg preserved in the body cavity. This is the first such example known in the fossil record. The bird was named Avimaia schweitzerae (literally ‘Schweitzer’s mother bird’) in honour of Dr Mary Schweitzer for her ground-breaking work on soft-tissue finds in fossils.
“Despite being malformed, the egg is excellently preserved, including parts of the eggshell that are rarely seen in the fossil record, such as traces of the egg membrane and the cuticle, which are mostly made of proteins and other organic materials.”
The two-dimensionally preserved egg had between four and six layers in cross-section, suggesting an abnormal double-layering. Lead author Dr Alida Bailleul explained:
“The reproductive system of this female bird was not behaving normally. The egg shell consists of two layers instead of one as in normal healthy bird eggs, indicating the egg was retained too long inside the abdomen. This condition often occurs in living birds as a result of stress. The unlaid egg then gets coated in a second layer—or sometimes more—of eggshell.”
In this case the Noahic Flood some 4,500 years ago provides not only the traumatic experience that likely led to the unlaid double-layered egg, but also the circumstances needed (rapid burial in mineral-rich sediment) to preserve both egg and mother as a fossil.
- Bailleul, A. and 7 others, An Early Cretaceous enantiornithine (Aves) preserving an unlaid egg and probable medullary bone, Nature Communications 10:1275, 2019.
- Bell, V., Ancient bird that died 110-million-years-ago is found perfectly preserved with an egg inside its body, dailymail.co.uk, 20 Mar 2019.
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