First Mesozoic bird eggs from Korea, Onggwanoolithus
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Ben Creisler
Feb 20, 2026, 2:40:02 PMFeb 20
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Ben Creisler
Aphaedo is documented as a key mid-Cretaceous theropod egg locality in Korea.
Five distinct theropod-affinity ootaxa are identified from a single site.
A new avialan-type egg, Onggwanoolithus, is the first described from Korea.
Egg microstructure indicates ornithuromorph affinities, including crown birds.
Nesting patterns suggest paleoecological or preservational bias in egg assemblages.
Abstract
The Mesozoic record of the Korean Peninsula is remarkable in both the abundance and diversity of bird footprints, indicating that a wide range of taxa inhabited this region for an extended interval during the Cretaceous. In contrast, egg fossils attributable to Avialae have not previously been reported. Here, we report a new tiny theropod egg taxon, Onggwanoolithus aphaedoensis oogen. et oosp. Nov. based on multiple eggs from the mid-Cretaceous Ilseongsan Formation of Aphae Island (Aphaedo), which is described using micro-X-ray computed tomography and histological data. These eggs lack surface ornamentation and, in thin section, show three distinct layers, characteristics uniquely observed within Avialae, including in crown birds. Onggwanoolithus represents one of the earliest records of an egg showing these characteristics. Theropod egg miniaturization with concomitant shell thinning is first seen in the Late Jurassic, with very few Early or mid-Cretaceous records before becoming more abundant in the Late Cretaceous. We also describe the Aphaedo site, which preserves five ootaxa attributed to theropods, including Macroleongatoolithus, a second type of elongatoolithid, as well as dendroolithid, prismatoolithid eggs, and Onggwanoolithus. This theropod-dominated oofauna is unique among Korean Cretaceous egg sites and most closely resembles select theropod-rich egg assemblages reported from other parts of Asia and North America. Such assemblages may reflect nesting preferences and/or preservational biases. One of Aphaedo egg types is preserved in an intact nest structure and two others are known from largely intact eggs, suggesting limited or no transport of some eggs prior to deposition in overbank deposits of a floodplain environment.
A new paper:
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Onggwanoolithus aphaedoensis oogen. et oosp. nov.
Hyemin Jo, Jongyun Jung, Minguk Kim, Min Huh & Julia A. Clarke (2026)
Description of the first Mesozoic bird eggs from Korea and a new mid-cretaceous theropod-dominated egg locality
Palaeogeography, Palaeoclimatology, Palaeoecology 113653
doi: https://doi.org/10.1016/j.palaeo.2026.113653
https://www.sciencedirect.com/science/article/abs/pii/S0031018226001161
Highlights
Hyemin Jo, Jongyun Jung, Minguk Kim, Min Huh & Julia A. Clarke (2026)
Description of the first Mesozoic bird eggs from Korea and a new mid-cretaceous theropod-dominated egg locality
Palaeogeography, Palaeoclimatology, Palaeoecology 113653
doi: https://doi.org/10.1016/j.palaeo.2026.113653
https://www.sciencedirect.com/science/article/abs/pii/S0031018226001161
Highlights
Aphaedo is documented as a key mid-Cretaceous theropod egg locality in Korea.
Five distinct theropod-affinity ootaxa are identified from a single site.
A new avialan-type egg, Onggwanoolithus, is the first described from Korea.
Egg microstructure indicates ornithuromorph affinities, including crown birds.
Nesting patterns suggest paleoecological or preservational bias in egg assemblages.
Abstract
The Mesozoic record of the Korean Peninsula is remarkable in both the abundance and diversity of bird footprints, indicating that a wide range of taxa inhabited this region for an extended interval during the Cretaceous. In contrast, egg fossils attributable to Avialae have not previously been reported. Here, we report a new tiny theropod egg taxon, Onggwanoolithus aphaedoensis oogen. et oosp. Nov. based on multiple eggs from the mid-Cretaceous Ilseongsan Formation of Aphae Island (Aphaedo), which is described using micro-X-ray computed tomography and histological data. These eggs lack surface ornamentation and, in thin section, show three distinct layers, characteristics uniquely observed within Avialae, including in crown birds. Onggwanoolithus represents one of the earliest records of an egg showing these characteristics. Theropod egg miniaturization with concomitant shell thinning is first seen in the Late Jurassic, with very few Early or mid-Cretaceous records before becoming more abundant in the Late Cretaceous. We also describe the Aphaedo site, which preserves five ootaxa attributed to theropods, including Macroleongatoolithus, a second type of elongatoolithid, as well as dendroolithid, prismatoolithid eggs, and Onggwanoolithus. This theropod-dominated oofauna is unique among Korean Cretaceous egg sites and most closely resembles select theropod-rich egg assemblages reported from other parts of Asia and North America. Such assemblages may reflect nesting preferences and/or preservational biases. One of Aphaedo egg types is preserved in an intact nest structure and two others are known from largely intact eggs, suggesting limited or no transport of some eggs prior to deposition in overbank deposits of a floodplain environment.
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Gregory Paul
Feb 21, 2026, 2:36:22 PMFeb 21
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I have been trying to find a DIRECT SIDE view (oblique is of no use) photograph of the ENTIRE Chicago full size sculpture of Sue from the tip of the nose to the tip of the tail, but cannot find any. If anyone has one, or knows where such is, please let me know. If anyone lives near the museum and can take a pic please contact me.
GSPaul
Ben Creisler
Feb 21, 2026, 4:20:40 PMFeb 21
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Ben Creisler
I'm not sure if these will help or if you have already seen them.
There are partial side views on the Blue Rhino Studio website, one of the model to the base of the tail and another of the hips to most of the tail.
Also a blog post photo almost directly side on:
On Sat, Feb 21, 2026 at 11:36 AM 'Gregory Paul' via Dinosaur Mailing Group <DinosaurMa...@googlegroups.com> wrote:
I have been trying to find a DIRECT SIDE view (oblique is of no use) photograph of the ENTIRE Chicago full size sculpture of Sue from the tip of the nose to the tip of the tail, but cannot find any. If anyone has one, or knows where such is, please let me know. If anyone lives near the museum and can take a pic please contact me.GSPaul
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Gregory Paul
Feb 21, 2026, 4:37:28 PMFeb 21
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The top image in the 2nd link is close but not quite. Looking for a direct side view that can measure full length of model so can compare at same scale to my profile-skeletal of Sue.
GSPaul
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