Organism · Birds and early avialans
Dasornis emuinus
Source time context (not species duration) · ≈ 56–33.9 Ma
Inferred life reconstruction
Dasornis emuinus
Overview
This seabird had tooth-like projections lining the edges of its bill. Dasornis emuinus is a species in the group of giant bony-toothed birds. Picture an unfamiliar apparatus added to the familiar face of a bird.[1]
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Key facts
The projections on the bill are false teeth formed by outgrowths of the jawbone rather than true teeth. This is why the group is called bony-toothed birds. They developed another structure along the bill edges without regaining true teeth.[1][2]
Time and place
Picture the seas of the Early Eocene, around 50 million years ago. An important skull came from the London Clay on the Isle of Sheppey in present-day Kent, UK. A fossil from the island's coast preserves the face of an ancient seabird.[1]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
The partial skull studied preserves the shape and grooves at the rear of the bill. A 2008 study linked this bird with giant pelagornithids with highly developed wings. The combination of large wings and an elongated bill provides a focus for observation.[1]
The wingspan of Dasornis emuinus was estimated at about 3.5–4.5 m in a 2010 study.[5]
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Habitat and reproduction
The pelagornithid family to which this bird belongs obtained food from the sea. The bony projections of the bill are interpreted as a device for gripping slippery prey. Comparison with related birds allows us to examine the life of a seabird that would have used food such as fish.[2]
Fossil discovery
Large bird fragments from the London Clay once went by several names. In 2008, Mayr studied the relatively substantial skull SMNK-PAL 4017 and brought these fossils together as Dasornis emuinus. The new fossil also clarified the relationships between the names.[1]
References
- Mayr (2008), “A skull of the giant bony-toothed bird Dasornis (Aves: Pelagornithidae) from the Lower Eocene of the Isle of Sheppey,” Palaeontology 51(5):1107–1116.
- Bourdon et al. 2010 — Pseudotoothed birds from the Early Tertiary of Morocco
- Mayr (2008), “A skull of the giant bony-toothed bird Dasornis (Aves: Pelagornithidae) from the Lower Eocene of the Isle of Sheppey,” Palaeontology 51(5):1107–1116.
- Widrig, Navalón & Field (2024) · Paleoneurology of stem palaeognaths clarifies the plesiomorphic condition of the crown bird central nervous system · Journal of Morphology285(6):e21710
- Bourdon et al. (2010) — Early Cenozoic pseudotoothed birds from Morocco
Research questions
How many times might giant wings have arisen during this group's evolution? The 2008 study proposed a hypothesis linking Dasornis with later giant bony-toothed birds. Comparing heads and wings together allows us to trace the history of changes in body size.[1]
Observation
Begin by examining the elongated bill and the projections along its edges.[1][2]
Related organisms
Lithornis vulturinusBirds and early avialansSource time context (not species duration) · ≈ 59–48 MaDifferent birds of the London Clay
Dasornis and Lithornis are Early Eocene birds known from the London Clay in present-day Britain. Read head material from a seabird with tooth-like bill projections alongside that of a palaeognath bird, and examine their different forms within the same broad geological setting.