Better data on Protictis shifts it from bats to carnivores

Updated January 06, 2016 based on additional taxa.

This is what happens
when you get data more directly. In this case data that used to come from a freehand drawing (Fig. 1) now comes from a photo of Protictis (Cope 1883, Mac Intyre 1966; middle Paleocene; Fig. 1). As everyone knows, in Science, you have to be willing to let go of any pet hypotheses of relationships whenever better data recover different results. And this is how you do it: You just do it!

Figure 1. Protictis skull based not on a free hand drawing, but on this published photo.

Figure 1. Protictis skull based not on a free hand drawing, but on this published photo from Mac Intyre 1966. Note all difference with the original freehand drawing, also from Mac Intyre 1966. Preserved elements about 5 cm in length.

More than five years ago,
before ReptileEvolution.com was first created with about 260 taxa in the large reptile tree (now 915 taxa), Protictis was not included in that data matrix. Rather it nested in a separate ‘bat’ cladogram between Chriacus and bats based on data gleaned from the line art reconstruction in Mac Intyre 1966  Now Protictis joins the LRT with data based on a published photo (Fig. 1) in Mac Intyre 1966. Now it nests with Vulpavus, Deltatherium and the carnivore specimen of Ectocion. all within the Carnivora. That makes sense based on several traits, including the very large canine teeth.

That early Palaeocene date
along with the rather derived node occupied by Protictis anticipate (currently without much evidence) a wider radiation of the Carnivora during the Jurassic and Cretaceous than prior workers surmised. An early member of this clade, Vincelestes, is found in Early Cretaceous strata, yet even at that early date, already shows distinctly derived traits. Phylogenetic and chronological bracketing predict that mongoose- and civet-like carnivore taxa will be found in Jurassic and Cretaceous strata.

I’ll have to go back and update
any figures that have not yet been updated. Here (Fig. 2) is the latest on bat origins (now sans Protictis). And there’s more here. It’s the same topology, only without Protictis now.

Palaechthon has been added today
but it nests, as it did before, with the dermopteran, Cynocephalus.

Figure 2. Known bat ancestors to scale. Click to enlarge.

Figure 2. Known bat ancestors to scale. Click to enlarge. Protictis is no longer among them. It is likely that bat ancestors never got as large as Chriacus, but it is the only representative of that morphology, between Ptilocercus and bats.

And we can still use Ptilocercus as a pretty good model
for bat origins. It nests close to their ancestry without showing signs of great deviation.

Figure 4. Ptilocercus, Icaronycteris and a hypothetical transitional taxon based on the ontogenetically immature wing of the embryo Myotis. If you're going to evolve wings it looks like you have to stop using them as hands early on. Note in the bat embryo there is little indication of inter-metacarpal muscle. That area looks identical to the web.

Figure 3. Ptilocercus, Icaronycteris and a hypothetical transitional taxon based on the ontogenetically immature wing of the embryo Myotis. If you’re going to evolve wings it looks like you have to stop using them as hands early on. Note in the bat embryo there is little indication of inter-metacarpal muscle. That area looks identical to the web.

 

References
Cope ED 1882. Synopsis of the Vertebrata of the Puerco epoch. Proceedings of the American Philosophical Society 20:461-471.
Mac Intyre GT 1966. The Miacidae (Mammalia, Carnivora) Part 1. The systematics of Ictidopappus and Protictis. Bulletin of the American Museum of Natural History 131(2):115-210.

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