Probable vs Plausible

There are inevitably few certainties about reconstructing some parts of extinct animals. In the case of feathers on dinosaurs for example, this does seem to generate some rather odd and to my eye, unnecessary commentary or controversy. There are some things that are known but others that can only be inferred based on the available evidence. More importantly, especially when it comes to things like palaeoart in all its forms, I think you have to permit what is plausible even if it is not necessarily the most likely of outcomes.

The reconstruction of Compsoganthus on here drew criticism for a lack of feathers. However, while there are certainly feathered compsoganthids like Sinocalliopteryx and Sinosauropteryx, Juravenator certainly preserves scales and only questionable feathers. Given that the clade as a whole likely represent the first appearance of feather-like structures, it is entirely plausible that some were ‘bald’. Even if there were quite a few more taxa known with feathers, it would still not be utterly outlandish to suggest that there were feather-less taxa out there in the compsoganthid family given what we know of Juravenator and the patchy nature of the feathers in Sinosauropteryx. It’s plausible, certainly.

Looking at something like Linheraptor though, and a lack of feathers seems much less likely, and extensive coverage looks probable. There are loads of dromaeosaurs with feathers, in fact pretty much every specimen preserved where feathers might be there (because the preservational conditions are right), they are there. We know that their near relatives like the troodontids and birds are feathered too, as are things like the oviraptorosaurs too. So a truly featherless dromaeosaur is not really plausible, but at best highly improbable, and a partly feathered one is on the borders of plausibility. It may not be the most likely, but can’t be eliminated and I would not be critical of a piece of art or model that reconstructed Linheraptor without a full coat of feathers.

On a similar note, I’ve written before about unusual behaviours and the giant eyes of bush-babys which stretch the limits of what might be expected for how certain animals act or the extremes their anatomy can reach. But these are outliers – they are possible and that means the idea that other extinct animals might be similar is plausible, but it does not make it likely. You could hypothesise that an apparently un-arboreal ornithopod might do OK in the trees at least on occasion because goats can, but this is merely a possibility, not a likelihood. Admittedly these things are somewhat ephemeral and judging the odds or differences between possible / plausible / probable can be tricky, but in general the differences, especially towards the extremes are quite clear and these are worth considering when trying to reconstruct missing anatomy and especially behaviour and ecology. You be aware of what is possible or the statement “goats don’t / cannot climb trees” can quickly be shown to be wrong, but then so too is “goats are adapted /prefer to live in trees” and getting the difference right is important.

7 Responses to “Probable vs Plausible”

  1. 1 Marc Vincent 01/12/2010 at 6:35 pm

    Given compsognathids’ integument, would you consider patchy primitive feather-like structures on tyrannosaurs (ie. the big, derived ones, as opposed to ‘tyrannosauroids’ more generally) to be within the realms of plausibility? Thomas Holtz certainly seems keen on the idea.

    (Fantastic blog by the way – long-time reader, first meaningful comment!)

    • 2 David Hone 01/12/2010 at 6:44 pm

      I have rather an inside knowledge on that which i can’t talk about. *However*, I’d go along with this. It’s not clear if Dilong had a full body covering, and we do have skin impressions suggesting that some big tyrannosaurs had no itegumentary coverings (at least, that which is preserved in the impression). Add that together and it’s possible that even Dilong had a patchy covering and so it’s perfectly plausible that the bigger ones did too.

      Glad you like the blog.

  2. 3 El PaleoFreak 02/12/2010 at 12:09 pm

    “Given that the clade as a whole likely represent the first appearance of feather-like structures”

    Forgot Tianyulong? ;o)

    • 4 David Hone 02/12/2010 at 12:22 pm

      Joking aside, one could argue that even IF Tianyulong filaments and feathers / proto-feathers are homologous, those on the tyrannosaurs / compsoganthids are among the earliest in a temporal sense given that Juraventaor is from the Late Jurassic.

      So there is still an escape route with a bit of semantic juggling! 😉

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