The Human Reptile?

Reptiles, from Nouveau Larousse Illustré, 1897-1904: Notice the inclusion of amphibians (below the crocodiles).

Reptiles, from Nouveau Larousse Illustré, 1897-1904: Notice the inclusion of amphibians (below the crocodiles).

A long time ago animals were divided into “mammals” and “reptiles” from Latin repere “to crawl, creep”.
Reptiles were the cold blooded, scaly creatures who lurked in cold water laid eggs and were basically “not nice” like fluffy furry mammals. Then along came James Cooke, the discovery of Australia and with it the Platypus an egg-lay “furry thing” to confuse the distinction as now mammals could also lay eggs.
Then recently it was realised that Birds were  closely related to dinosaurs. Even as late as 1999 when the BBC produced walking with Dinosaurs and it was still believed that dinosaurs were cold blooded so were scaly like lizards or at least free of surface “fluff”. So, the BBC have small dinosaurs with no covering at all in icy conditions looking about as warm as stuffed turkeys in the snow.
Leaellynasaura in winter forest 1999

Leaellynasaura in winter forest 1999

But a warm covering wasn’t “allowed” because Reptiles were cold blooded and therefore scaly and fluffless. They couldn’t be warm blooded or “fluffy” like “nice” hair covered mammals.
However, I’ve long been suspicious that just in other areas of academia, in the classification of species, academics are letting their own perceptions interfere with science. Mammals may be more closely related to some groups in the previous “reptile” class than to others.
Looking at Wakopedia (my name for Wikipedia as it’s far from credible after Connolley) it was connolley like asserted that there were two distinct groups of amonites (the group that includes, reptiles, mammals and birds). This group was divided into Sauropsids (reptiles and birds) and Synapsida (mammals). And furthermore:

“Sauropsida is distinguished from Synapsida, which includes mammals and their fossil ancestors.”

So, that seemed conclusive. Mammals were very distinct from the reptiles. However in the same way “CO2 caused 20th century warming” is asserted without evidence, so this emphatic assertion that mammals are distinct was asserted but details were thin on the ground. So, I read on, and the reality appears to be far more complex:

In 1956, D.M.S. Watson observed that sauropsids and synapsids diverged very early in the reptilian evolutionary history [i.e. he asserted] , and so he divided Goodrich’s Protosauria between the two groups. He also reinterpreted the Sauropsida and Theropsida [mammal like reptiles] to exclude birds and mammals respectively, making them paraphyletic, unlike Goodrich’s definition.

This is all beginning to sound very arbitrary and in particular the statement about them being two groups both descending from “amniotes” is as clear as mud:

[Synapsids – (i.e. mammals-like)] are easily separated from other amniotes [the group of Reptile+ mammals] by having a temporal fenestra, an opening low in the skull roof behind each eye, leaving a bony arch beneath each; this accounts for their name. Primitive synapsids are usually called pelycosaurs; more advanced mammal-like ones, therapsids.

The Reptiles, mammals, birds and turtles

The Reptiles, mammals, birds and turtles (source)

We have an assertion that there are two groups: Synapsids & Sauropods, both descending from Amniotes as shown as the lower groups on the diagram to the right. But the paragraph is talking about differences between the mammal-like group from its (supposed) ancestral group of Amniotes, not between the mammal like and the reptile-like group.
As written it sounds as if Amniotes are an early form of the Reptile-like group and both were distinct from the mammal-like group. It was all starting to sound a bit wishy washy and arbitrary so, I thought I’d look at some specific groups to see how they are thought to be related. Eventually I came to Turtles & Tortoises. Now here I found some controversy and controversy always highlights problems and where things just do not fit. So what is this controversy? As the drawing above shows, there is a question where turtles fit:

Their exact ancestry [of turtles] has been disputed. It was believed they are the only surviving branch of the ancient evolutionary grade Anapsida, … All anapsid skulls lack a temporal opening, while all other extant amniotes have temporal openings (although in mammals the hole has become the zygomatic arch).

So, now we seem to have two main groups:

  1. Turtles – only surviving “Anapsida” distinguished by ” skulls lack a temporal opening,”
  2. Mammals and other reptiles whose skulls have a temporal opening.

So, mammals are more closely related to crocodiles than turtles – in other words, if turtles and crocodiles are reptiles, then so are we! But reading further, it seemed I was wrong, because the DNA evidence seems to strongly contradict this:

All molecular studies have strongly upheld the placement of turtles within diapsids; some place turtles within Archosauria, or, more commonly, as a sister group to extant archosaurs. (bird-like reptiles)

That seemed conclusive: Turtles are found to be most like bird-like reptiles, butit continued.

… However, one of the most recent molecular studies, published in February 2012, suggests that turtles are most closely related to the lepidosaurs (lizards, snakes, and tuataras – i.e. reptiles unlike birds).

One group of researchers are stating turtles are in a group with bird-like reptiles, and then woosh … along comes research saying they are more closely related to the other group of reptiles which we could call the “unlike Bird Reptiles”. How can this be? As Wakopedia says:

Reanalysis of prior phylogenies suggests that they classified turtles as anapsids both because they assumed this classification (most of them were studying what sort of anapsid turtles are) and because they did not sample fossil and extant taxa broadly enough for constructing the cladogram.

So, they were found to be Anapsids (Bird-like) because the researchers only tested how close they were to other Anapsids. And they were not found to be lepidosaurs or like Lizard-like because until the last study, no one had checked. And just like the Climate, how do academics respond when it all goes wrong? They redefine the meaning of words so that they mean what they want them to say:

Gauthier, Kluge and Rowe (1988) attempted to redefine Anapsida so it would be monophyletic, defining it as the clade containing “extant turtles and all other extinct taxa that are more closely related to them than they are to other reptiles”. This definition explicitly includes turtles in Anapsida;

In other words when the facts don’t fit, just change your definition so that you redefine the group as “Turtles are in the bird-like reptiles because I say so”.
But it gets worse:

Gauthier, Kluge and Rowe (1988) themselves included only turtles and Captorhinidae in their Anapsida, while excluding the majority of anapsids in the traditional sense of the word from it. In addition, Tsuji and Müller (2009) noted that the name Anapsida implies a morphology (lack of temporal openings) that is in fact absent in the skeletons of a number of taxa traditionally included in the group. …  The presence of temporal openings in the skulls of these taxa makes it uncertain whether the ancestral reptiles had an anapsid-like skull as traditionally assumed or a synapsid-like skull instead.

So, Turtles do not really fit into either the bird-like or lizard-like groups. So what is the problem here? Why are academics jumping through hoops to try to include Turtles as part of the Bird-like reptiles? Why isn’t the evidence that they are as closely related to unlike-bird reptiles being considered?

New family tree of Reptilia

New family tree of Reptilia

Now we have this group diverging from the amphibians and the first split in this group which includes all the reptiles was between the turtles and another group of reptiles which include, crocodiles, birds, lizards, snakes, and … mammals like humans.
This I think is what is causing the academics to jump through hoops and redefine classes to include groups by definition rather than common sense:
Academics don’t like the idea of being considered “reptiles”.
In other words, for all the nonsense about the conflict between supposed “science” and “evolutionists”, it turns out that academics are just as reluctant to follow the logical evidence and put mammals in the class of reptiles as their predecessors were to put humans with apes.


And just to show that this is a realistic proposal, I found this after I published which as I suggest shows Turtles branching off the “Reptialian” group before mammals.


This entry was posted in Academia, General, My Best Articles, Proposals and tagged , , , . Bookmark the permalink.