In a comment on the last post, Mike wrote, “perhaps the pneumaticity was intially a size-related feature that merely failed to get unevolved when rebbachisaurs became smaller”. {.wp-image-6447 .size-large aria-describedby=“caption-attachment-6447” loading=“lazy” attachment-id=“6447” permalink=“http://svpow.com/2012/06/28/hot-sauropod-news-part-1-rampant-pneumaticity-in-saltasaurines/caudal-pneumaticity-in-saltasaurines-cerda-et-al-2012-fig-1/”

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I recently reread Dubach (1981), “Quantitative analysis of the respiratory system of the house sparrow, budgerigar and violet-eared hummingbird”, and realized that she reported both body masses and volumes in her Table 1. For each of the three species, here are the sample sizes, mean total body masses, and mean total body volumes, along with mean densities I calculated from those values.* * House sparrow, Passer domesticus , n = 16,