Paraphyletic and Monophyletic taxa #Tree-of-life

Before we continue in our series to talk about current research and what Ocean Wolf can offer you, this week, we will take a step back to university and school and look at evolution and systematics.
Recently, we saw a post that Turtles would be one of the "oldest reptile groups".
Ocean Wolf founder Paul commented that turtles are not reptiles, and that "reptiles" are, in general, a paraphyletic group; at least one of the commentators on that post wondered why this matter.
First, a clear understanding of the systematics reflects on the evolution of the taxa. Suppose we don't recognize Monophyletic and Paraphyletic groups. In that case, we come to false conclusions about the evolutionary process and development of organisms, in this case vertebrates (which includes ourselves).
Reptilia or reptiles are considered paraphyletic groups as they are artificially grouped due to characteristics like scales, cold-blooded, etc.
Traditionally many of us count as reptiles Crocodiles, Lizard and Snakes etc. However, anatomical characteristics like the mandibular fenestra (in the lower jaw) and the high and narrow skull suggest that Birds and Crocodiles are related (the Witmer Lab at the university of Ohio has some great hashtag#D models to visualize similarities: https://lnkd.in/gUk7ZEs7 & https://lnkd.in/gMmShu47). Crocodiles, Birds and non-avian Dinosaurs form the monophylum Archosaurs. In contrast, lizards and snakes form the monophylum known as Squamata, closely related to the Tuatara (the only living member of the Rhynchocephalians). Classically, in many trees, turtles form the branch before the Amphibians in the Vertebrate tree. However current studies of genetic development and the scaling of traits (the relationship between character and body size) started a new discussion about the position of Testudines (turtles) within the tree of vertebrates (Werneburg & Sanchez-Vilagra 2009, Zardoya & Meyer 1998, McIvor 2011, Hallmann & Griebeler 2018).
Back to the question, "Why does this matter"?
If we count turtles as reptiles and assume that the reptiles are a monophylum, we will need to explain where the outer bone structure (shell) is in all other reptiles, why turtles have no scales, where the mandibular fenestra is in all other reptiles besides the dinosaurs, and the list goes on. Hence, such an assumption would require many (unnecessary and in-exploratory) assumptions regarding the evolution of vertebrates.
hashtag#systematics hashtag#evolution hashtag#treeoflife hashtag#education hashtag#heertohelp @www.ocean-wolf.com
Images:
Tree of life of the Amniota after Hallmann & Griebeler 2018 Fig.1