Yes, Virginia, elephants are reptiles, too!

Updated July 2, 2016 with additional mammals on the cladogram. Updated July 10, 2016 with a revised skull for Elephas.

Today starts a three-day weekend in America
as we celebrate our independence Monday, July 4, which gives me lots of time to add taxa to the large reptile tree (still fully resolved at 712 taxa).

One taxon added today is Elephas,
the Indian elephant. And just as birds are dinosaurs because they descend from dinosaurs, elephants are reptiles, because they descend from reptiles that diverged from basal tetrapods some 340 mya in the Viséan (with lots of taxa in between demonstrating a gradual accumulation of derived traits.)

So far,
here’s where elephants nest in the large reptile tree (subset Fig. 1):

Figure 1. Subset of the large reptile tree with only a few mammals nested at present. More to come! Differences from traditional trees may be attributed to convergence (here the plant eaters nest together) or we may have found a new topology. Perhaps the future will reconcile the two trees.

FFigure 1. Subset of the large reptile tree with only a few mammals nested at present. More to come! Differences from traditional trees may be attributed to convergence (here the plant eaters nest together) or we may have found a new topology. Perhaps the future will reconcile the two trees.

Before anyone gets their panties in a bunch,
because taxa are not nesting with the traditional mammal sisters listed in Wikipedia, often as recovered by molecule analyses, remember, this is a short and growing list of mammals. DNA and morphology sometimes don’t match. And the character list was created for non-mammals. Still they’re doing a pretty good job. The herbivores are nesting with other herbivores here. Elephants don’t nest with ungulates in traditional trees.

Figure 2. Skull of Elephas maximus with color overlays. Most of the bones are fused to one another, so this tracing is provisional, pending confirmation and/or better data. Compare to the skull of Procavis (Fig. 3).

Figure 2. Skull of Elephas maximus with color overlays. Most of the bones are fused to one another, so this tracing is provisional, pending confirmation and/or better data. Compare to the skull of Procavis (Fig. 3).

Over the next few days
as more taxa are added let’s see if the tree topology changes to reflect traditional nestings or not. We’ve gained new insights before. We might do it again.

Figure 3. Procavis (extant rock hyrax) is a primitive relative to Elephas (figure 2).

Figure 3. Procavis (extant rock hyrax) is a primitive relative to Elephas (figure 2). Not many extant mammals have their skull bones identified, so this is provisional pending a better education in mammal skulls. Digimorph.org image used with permission.

 

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