Janavis

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Janavis finalidens is an extinct toothed bird from the Late Cretaceous of Belgium. It belongs to a group called Ichthyornithes, and it helps scientists understand how modern birds evolved. The genus name combines the Roman god Janus with the word for bird, and the species name means “ending tooth.”

Discovery and science
- The fossil was found in the Maastricht Formation near Eben Emael, Belgium, and dates to about 66.8 million years ago, not long before the dinosaur–bird boundary event.
- It was first reported in 2002 as Europe’s last Mesozoic bird and was formally described in 2022.
- The holotype is a rock block (NHMM RD 271) that mostly hid parts of the skull and some bones. CT scanning in 2021 revealed more of the skeleton inside, including neck and back bones, the shoulder area, a humerus, and part of a leg.

Size and appearance
- Janavis was relatively large for its group, with an estimated wingspan of about five feet and a body weight around 1 to 1.6 kilograms.

Key features and why it matters
- It had many air-filled bones (pneumatization) in the back and chest region, and distinctive features in the skull that allowed the upper jaw to move up and down.
- This jaw mobility is similar to modern birds in the group Neognathae and differs from the rigid palate seen in Paleognathae (the group that includes flightless birds like ostriches and kiwis).
- Because Janavis sits near the base of the modern-bird lineage, its skull structure suggests that a rigid palate in Paleognathae likely evolved independently after these birds split from other lineages.

Overall, Janavis finalidens provides important clues about the early evolution of birds and how some key features of modern birds developed. The fossil is housed at the Maastricht Natural History Museum, with further study conducted by researchers from Cambridge and elsewhere.