• HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
Saturday, September 6, 2025
BIOENGINEER.ORG
No Result
View All Result
  • Login
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
  • HOME
  • NEWS
  • EXPLORE
    • CAREER
      • Companies
      • Jobs
        • Lecturer
        • PhD Studentship
        • Postdoc
        • Research Assistant
    • EVENTS
    • iGEM
      • News
      • Team
    • PHOTOS
    • VIDEO
    • WIKI
  • BLOG
  • COMMUNITY
    • FACEBOOK
    • INSTAGRAM
    • TWITTER
No Result
View All Result
Bioengineer.org
No Result
View All Result
Home NEWS Science News Biology

New Cretaceous fossil sheds light on avian reproduction

Bioengineer by Bioengineer
March 20, 2019
in Biology
Reading Time: 3 mins read
0
IMAGE
Share on FacebookShare on TwitterShare on LinkedinShare on RedditShare on Telegram

IMAGE

Credit: Barbara Marrs

A team of scientists led by Alida Bailleul and Jingmai O’Connor from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences reported the first fossil bird ever found with an egg preserved inside its body. Their findings were published on March 20 in Nature Communications.

The new specimen, representing a new species, Avimaia schweitzerae, was discovered in 110-million-year-old deposits in northwestern China. It belongs to a group called the Enantiornithes (“opposite birds”), which were abundant all around the world during the Cretaceous and co-existed with the dinosaurs.

The new fossil is incredibly well preserved, including the remains of an egg inside its abdomen (Fig. 1). Because the specimen is crushed flat, it was only after a small fragment was extracted and analyzed under the microscope that the team realized that the unusual tissue was an egg.

Detailed analysis of the eggshell fragment revealed a number of interesting facts indicating 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. This abnormality has also been documented in sauropod dinosaurs, as well as in many fossil and living turtles.

In addition, the eggshell preserved in Avimaia was extremely thin – thinner than a sheet of paper – and did not show the correct proportions of healthy eggs. (Note that avian eggshells consist of three sublayers with particular dimensions.)

These abnormalities suggest that the preserved egg may have been the cause of death of this “mother bird.” Egg-binding, in which the egg becomes stuck inside the body causing death, is a serious and lethal condition that is fairly common in small birds undergoing stress.

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.

Scanning electron microscopy revealed that the cuticle (the outer most protective layer of the eggshell) was made up of very small spherules of minerals. This type of cuticle morphology would be expected for birds that partially burry their eggs, as it has already been proposed to be the case for enantiornithines (Fig. 2). Finding this morphology in Avimaia also supports the hypothesis that a cuticle with protective spherules represents the ancestral condition for avian eggs.

Female birds about to lay eggs deposit a unique bone tissue found inside the empty spaces of their skeleton, which serves as a calcium reservoir for the developing eggshell. Some researchers have argued that this tissue, called medullary bone, is present in other fossils (e.g., other fossil birds), as well as some non-avian dinosaurs and pterosaurs. However, some of these identifications were ambiguous.

Analysis of a fragment of leg bone from the new specimen revealed the presence of medullary bone. Avimaia is the only Mesozoic fossil in which additional morphological evidence of reproductive activity (i.e., the egg) supports the identification of medullary bone.

The preserved egg allows the specimen to be unequivocally identified as female, allowing scientists to test current hypotheses regarding sexual dimorphism (differences between genders).

This new specimen is arguably one of the most interesting Cretaceous fossil birds yet discovered, providing more reproductive information than any other Mesozoic fossil bird.

###

Media Contact
Alida Bailleul
[email protected]

Related Journal Article

http://dx.doi.org/10.1038/s41467-019-09259-x

Tags: ArchaeologyDevelopmental/Reproductive BiologyEvolutionOld World
Share13Tweet8Share2ShareShareShare2

Related Posts

Assessing Habitat Suitability for Italy’s Unique Vertebrate

Assessing Habitat Suitability for Italy’s Unique Vertebrate

September 6, 2025
blank

Gene Duplication Linked to Egg Weight in Chickens

September 5, 2025

Can Spider Cocoons Offer Antimicrobial Benefits?

September 5, 2025

Triazophos Effects on Immune Responses in Snakehead Fish

September 5, 2025
Please login to join discussion

POPULAR NEWS

  • blank

    Breakthrough in Computer Hardware Advances Solves Complex Optimization Challenges

    150 shares
    Share 60 Tweet 38
  • Molecules in Focus: Capturing the Timeless Dance of Particles

    142 shares
    Share 57 Tweet 36
  • New Drug Formulation Transforms Intravenous Treatments into Rapid Injections

    115 shares
    Share 46 Tweet 29
  • First Confirmed Human Mpox Clade Ib Case China

    54 shares
    Share 22 Tweet 14

About

We bring you the latest biotechnology news from best research centers and universities around the world. Check our website.

Follow us

Recent News

C-terminal Helix Charge Essential for Endolysin Function

Assessing Habitat Suitability for Italy’s Unique Vertebrate

Revolutionary Electromagnetic Device Enhances Spinal Injury Research

  • Contact Us

Bioengineer.org © Copyright 2023 All Rights Reserved.

Welcome Back!

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In
No Result
View All Result
  • Homepages
    • Home Page 1
    • Home Page 2
  • News
  • National
  • Business
  • Health
  • Lifestyle
  • Science

Bioengineer.org © Copyright 2023 All Rights Reserved.