Another look at the smallest adult pterosaur – AND its hatchling

Earlier we looked at the smallest adult pterosaur, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog. Here (Fig. 1) it is compared to an adult leaf chameleon, Brookesia micro, one of the smallest living lizards and to the Bee hummingbird, one of the smallest living birds. Also shown are their hatchlings and eggs.

Figure 1. The smallest of all adult pterosaurs, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog compared to scale with the living leaf chameleon (Brookesia micro) sitting on someone's thumb. Also shown are hypothetical eggs and hatchlings for both. These lepidosaurs had tiny eggs and hatchlings.

Figure 1. The smallest of all adult pterosaurs, B St 1967 I 276 or No. 6 in the Wellnhofer (1970) catalog compared to scale with the living leaf chameleon (Brookesia micro) sitting on someone’s thumb. Also shown are hypothetical eggs and hatchlings for both. These lepidosaurs had tiny eggs and hatchlings, relatively larger in the chameleon, based on pelvis size and average 1/8 size for other pterosaur hatchlings.

 

Traditional paleontologists
don’t buy the argument that No. 6 was an adult, even though it is much larger than the smallest lizard and about the size of the smallest bird. Worse yet, they refused to test it in phylogenetic analysis. So, the  impasse remains.

Figure 2. Smallest known bird, Bee hummingbird, compared to smallest known adult pterosaur, No. 6 (Wellnhofer 1970). Traditional workers consider this a hatchling or juvenile, but in phylogenetic analysis it does not nest with any 8x larger adults.

Figure 2. Smallest known bird, Bee hummingbird, compared to smallest known adult pterosaur, No. 6 (Wellnhofer 1970). Traditional workers consider this a hatchling or juvenile, but in phylogenetic analysis it does not nest with any 8x larger adults. This image is slightly larger than life size at 72dpi. Note the much smaller eggs produced by the tiny pterosaur. 

 

Pictures tell the tale.
You can see for yourself. No. 6 is substantially smaller than other tiny pterosaurs just as the bee hummingbird is substantially smaller than other hummingbirds.The hatchling was substantially smaller than both the leaf chameleon and bee hummingbird hatchlings based on their larger egg size/pelvis opening.

Earlier we looked at isometric growth in several pterosaurs, with hatchlings matching adults in morphology. Earlier we also took note of the danger of desiccation to hatchling pterosaurs until they reached a certain size/volume, so they probably roamed the leaf litter, which is probably when pterosaurs became quadrupeds and developed elongate metacarpals 4x.

References
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.

wiki/Pterodactylus

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2 thoughts on “Another look at the smallest adult pterosaur – AND its hatchling

  1. One important thing to notice is how the egg size/adult body ratio increases as size decreases. This says that the pterosaur no. 6 could not produce and egg that large, and the easiest explanation is that it could not produce an egg. The easier and simpler the explanation, the more likely it will withstand criticism.

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