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| Kongonaphon kely
Kammerer, Nesbitt, Flynn, Ranivoharimanana & Wyss, 2020
Illustration: Alex Boersma
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Abstract
Early members of the dinosaur–pterosaur clade Ornithodira are very rare in the fossil record, obscuring our understanding of the origins of this important group. Here, we describe an early ornithodiran (Kongonaphon kely gen. et sp. nov.) from the Mid-to-Upper Triassic of Madagascar that represents one of the smallest nonavian ornithodirans. Although dinosaurs and gigantism are practically synonymous, an analysis of body size evolution in dinosaurs and other archosaurs in the context of this taxon and related forms demonstrates that the earliest-diverging members of the group may have been smaller than previously thought, and that a profound miniaturization event occurred near the base of the avian stem lineage. In phylogenetic analysis, Kongonaphon is recovered as a member of the Triassic ornithodiran clade Lagerpetidae, expanding the range of this group into Africa and providing data on the craniodental morphology of lagerpetids. The conical teeth of Kongonaphon exhibit pitted microwear consistent with a diet of hard-shelled insects, indicating a shift in trophic ecology to insectivory associated with diminutive body size. Small ancestral body size suggests that the extreme rarity of early ornithodirans in the fossil record owes more to taphonomic artifact than true reflection of the group’s evolutionary history.
Keywords: body size, evolution, Dinosauria, Triassic, phylogeny
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| Anatomy of the maxilla of Kongonaphon kely gen. et sp. nov. (UA 10618). Right maxilla in right lateral and palatal views. |
Systematic Paleontology
Archosauria Cope, 1869
Avemetatarsalia Benton, 1999
Lagerpetidae Arcucci, 1986
sensu Nesbitt et al., 2009
Kongonaphon kely gen. et sp. nov.
Etymology. Name meaning “tiny bug slayer,” derived from kongona (Malagasy, “bug”) and φoν (variant of ancient Greek φoνeύς, “slayer”), referring to the probable diet of this animal; kely (Malagasy, “small”), referring to the diminutive size of this specimen.
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| Illustration of Kongonaphon kely, a newly described reptile near the ancestry of dinosaurs and pterosaurs, in what would have been its natural environment in the Triassic (~237 million years ago).
Illustration: Alex Boersma
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Significance:
Reptiles of the Mesozoic Era are known for their remarkable size: dinosaurs include the largest known land animals, and their relatives, the pterosaurs, include the largest creatures to ever fly. The origins of these groups are poorly understood, however. Here, we present a species (Kongonaphon kely) from the Triassic of Madagascar close to the ancestry of dinosaurs and pterosaurs, providing insight into the early evolution of those groups. Kongonaphon is a surprisingly small animal (estimated height, ∼10 cm). Analysis of ancestral body size indicates that there was a pronounced miniaturization event near the common ancestor of dinosaurs and pterosaurs. Tiny ancestral body size may help explain the origins of flight in pterosaurs and fuzzy integument in both groups.
Christian F. Kammerer, Sterling J. Nesbitt, John J. Flynn, Lovasoa Ranivoharimanana and André R. Wyss. 2020. A Tiny Ornithodiran Archosaur from the Triassic of Madagascar and the Role of Miniaturization in Dinosaur and Pterosaur Ancestry. PNAS. DOI: 10.1073/pnas.1916631117
A tiny ancient relative of dinosaurs and pterosaurs discovered
