A tiny 67 myo fossilized broken bone, unearthed in a quarry outside of Liège, Belgium in 2002, may cause a rewriting of how we think bird evolution progressed. Most modern birds have a jointed upper jaw which permits the upper half of their beak to move, but some, like emus, ostriches and rheas, have fused upper palates meaning that he top portion of the beak is far less mobile.
This fused palate is also found in dinosaurs, including the feathered ones that were ancestors to birds around today. This led researchers to conclude that birds such as emus and the like evolved first and that the mobile upper beak was a later development.
The full paper is Cretaceous ornithurine supports a neognathous crown bird ancestor, which can be accessed by request from Accepted version (Unknown, 172Kb), although here is the abstract from it:
I should note that an article in Science regarding this concludes with
This fused palate is also found in dinosaurs, including the feathered ones that were ancestors to birds around today. This led researchers to conclude that birds such as emus and the like evolved first and that the mobile upper beak was a later development.
The full paper is Cretaceous ornithurine supports a neognathous crown bird ancestor, which can be accessed by request from Accepted version (Unknown, 172Kb), although here is the abstract from it:
Abstract
The bony palate diagnoses the two deepest clades of extant birds: Neognathae and Palaeognathae1,2,3,4,5. Neognaths exhibit unfused palate bones and generally kinetic skulls, whereas palaeognaths possess comparatively rigid skulls with the pterygoid and palatine fused into a single element, a condition long considered ancestral for crown birds (Neornithes)3,5,6,7,8. However, fossil evidence of palatal remains from taxa close to the origin of Neornithes is scarce, hindering strong inferences regarding the ancestral condition of the neornithine palate. Here we report a new taxon of toothed Late Cretaceous ornithurine bearing a pterygoid that is remarkably similar to those of the extant neognath clade Galloanserae (waterfowl + landfowl). Janavis finalidens, gen. et sp. nov., is generally similar to the well-known Mesozoic ornithurine Ichthyornis in its overall morphology, although Janavis is much larger and exhibits a substantially greater degree of postcranial pneumaticity. We recovered Janavis as the first-known well-represented member of Ichthyornithes other than Ichthyornis, clearly substantiating the persistence of the clade into the latest Cretaceous9. Janavis confirms the presence of an anatomically neognathous palate in at least some Mesozoic non-crown ornithurines10,11,12, suggesting that pterygoids similar to those of extant Galloanserae may be plesiomorphic for crown birds. Our results, combined with recent evidence on the ichthyornithine palatine12, overturn longstanding assumptions about the ancestral crown bird palate, and should prompt reevaluation of the purported galloanseran affinities of several bizarre early Cenozoic groups such as the ‘pseudotoothed birds’ (Pelagornithidae)13,14,15.
The bony palate diagnoses the two deepest clades of extant birds: Neognathae and Palaeognathae1,2,3,4,5. Neognaths exhibit unfused palate bones and generally kinetic skulls, whereas palaeognaths possess comparatively rigid skulls with the pterygoid and palatine fused into a single element, a condition long considered ancestral for crown birds (Neornithes)3,5,6,7,8. However, fossil evidence of palatal remains from taxa close to the origin of Neornithes is scarce, hindering strong inferences regarding the ancestral condition of the neornithine palate. Here we report a new taxon of toothed Late Cretaceous ornithurine bearing a pterygoid that is remarkably similar to those of the extant neognath clade Galloanserae (waterfowl + landfowl). Janavis finalidens, gen. et sp. nov., is generally similar to the well-known Mesozoic ornithurine Ichthyornis in its overall morphology, although Janavis is much larger and exhibits a substantially greater degree of postcranial pneumaticity. We recovered Janavis as the first-known well-represented member of Ichthyornithes other than Ichthyornis, clearly substantiating the persistence of the clade into the latest Cretaceous9. Janavis confirms the presence of an anatomically neognathous palate in at least some Mesozoic non-crown ornithurines10,11,12, suggesting that pterygoids similar to those of extant Galloanserae may be plesiomorphic for crown birds. Our results, combined with recent evidence on the ichthyornithine palatine12, overturn longstanding assumptions about the ancestral crown bird palate, and should prompt reevaluation of the purported galloanseran affinities of several bizarre early Cenozoic groups such as the ‘pseudotoothed birds’ (Pelagornithidae)13,14,15.
I should note that an article in Science regarding this concludes with
Several skulls of its older Ichthyornis relative have been described in recent years with bones that suggested the bird’s upper palate might have been jointed, but the evidence was still fuzzy. Now, in the Janavis fossil, “the specific skull bone that materialized was the particular one we needed” to show the upper beak was flexible, Field says. Torres agrees. “It’s like a puzzle where that one piece was missing, and now we have it,” he says.
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