The Tiniest Wasp vs. The Tiniest Pterosaur Hatchling

Fairy Fly (Wasp)

Figure 1. Fairy Fly (Wasp) compared to two single-celled creatures, a paremecium and an amoeba.

The world’s smallest insect, one of the family of Fairy Wasps (or Fairy Flies ) has a body length of only 0.139 mm. I found the image of this Fairy Wasp alongside two single-celled animals (Fig. 1) to be fascinating and wondered how they would compare to the hypothetical hatchling of the world’s smallest pterosaur  B St 1967 I 276 (No. 6 in the Wellnhofer 1970 catalog (Fig. 2)), ostensibly the world’s smallest flying vertebrate.

A hypothetical hatchling No. 6

Figure 2. A hypothetical hatchling No. 6 (one-eighth the size of the adult) alongside a fly, a flea and the world's smallest insect, a fairy fly (fairy wasp). The fairy wasp is shown enlarged here (scaled in red) and to scale (barely visible). The fairy fly is enlarged in figure 1.

Every Picture Tells a Story
And this picture tells it all. A hatchling No. 6 would have been easy prey for a house fly, which is one more reason why such hatchlings may have preferred to hide and not fly. The first reason was the threat of desiccation blogged earlier due to a high surface to volume ratio (Hedges and Thomas 2001). Thankfully enough of these tiny pterosaurs survived the Late Jurassic to give rise to the several giant spectacular tapejarids and pteranodontids of the Cretaceous, all descendants of these tiny “fly cookies.”

Hedges SB and Thomas R 2001. At the Lower Size Limit in Amniote Vertebrates: A New Diminutive Lizard from the West Indies. Caribbean Journal of Science 37:168–173.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

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