Sean P. Modesto, Jason S. Naming taxa is an important endeavor in the documentation of life by systematists, whether it is conducted in the context of traditional rank-based classification or within a phylogenetic framework. Proponents of the phylogenetic approach distinguish between the diagnosis of a group and its definition Ghiselin, ; Rowe, , , and this distinction forms the basis for a phylogenetically based method of naming taxa formerly referred to as Phylogenetic Taxonomy de Queiroz and Gauthier, , , and now called Phylogenetic Nomenclature PN; Cantino et al.
Emphasis in naming has been placed on ancestry using phylogenetic definitions, and the widespread adoption of node- and stem-based definitions apomorphy-based definitions have yet to receive as widespread acceptance, but see Gauthier and de Queiroz, ; Anderson, ; Laurin and Anderson, has led to a proliferation of new names and definitions.
This shift in nomenclatural practice has, unfortunately, fostered a growth in redundant names and definitions for well-known taxa Benton, The PhyloCode Cantino and de Queiroz, has modified the rule of priority as used in other codes i. Unfortunately, it is now apparent that some of the definitions for well-known taxon names established early in the emergence of PN were not devised following conventions now widely accepted, by either defining groups in an overly restrictive manner, or via selection of reference taxa without due consideration of the ramifications of differing tree topologies Anderson, ; Laurin and Anderson, It has become evident in broad-scale amniote taxonomy that the first published definition for Reptilia Gauthier et al.
Recent morphological and molecular studies have challenged conventional hypotheses concerning the affinities of turtles, and this has led to unexpected and undocumented changes in the composition of the well-known taxon Reptilia, with additional ramifications for the nomenclature of some of its included taxa. We examine the consequences of the application of priority to the nomen Reptilia as our understanding of early amniote interrelationships has progressed over the past two decades, and offer a new definition that brings the phylogenetic concept of this taxon name into line with both currently accepted conventions of PN and historical usage.
This new definition corrects an error created by the combination of the selection of a higher taxon rather than a species as a specifier, and an unexpected topology. We believe that now is an appropriate time to examine the definitions established when PN was in its earliest stages, and hope to correct what we consider to be a poorly formulated definition upon publication of a binding PhyloCode.
To understand the motivations of some workers and their formation of phylogenetic definitions for the nomen Reptilia, it is important to review the history of this taxon. Reptilia was erected originally as a Class by Laurenti for the inclusion of tetrapods that were neither mammals nor birds.
Amphibians were included in Reptilia by Owen , and other authors, but following Haeckel's work that demonstrated reptiles, birds, and mammals shared a common reproductive strategy the amniotic egg , frogs, salamanders, and caecilians were placed unanimously in a separate taxon, Linnaeus' Amphibia. Hence, reptiles were primarily distinguished from birds and mammals by poikilothermy and lack of integumentary features such as hair and feathers e.
Fossil tetrapods that satisfied this diagnosis were placed within Reptilia.
However, some of the first fossils assigned to Reptilia were recognized by early workers to have conspicuously mammalian characteristics Owen, , ; Cope, , It was recognized early that synapsids were related more closely to mammals than to other fossil taxa included within Reptilia e. This view became entrenched as the classic hypothesis that explained the origin of mammals from reptiles Romer and Price, ; Romer, During the time that paleontologists were beginning to distinguish fossil synapsids from unequivocal reptiles, Haeckel distinguished reptiles, birds, and mammals from other tetrapods amphibians by placing them in a new taxon that he called Amniota, which was ignored as a taxon name although the concept was accepted in many subsequent published classifications e.
A more testable picture of amniote interrelationships appeared following the adoption of phylogenetic systematics Gaffney, ; Reisz, ; Gardiner, ; Heaton and Reisz, ; Gauthier et al. The emerging consensus Gauthier et al. Synapsida was defined as a stem-based group with Mammalia as its crown Rowe, , whereas Reptilia was defined as a node-based group using extant turtles, snakes, lizards, and crocodiles as reference taxa Gauthier et al.
Gauthier et al. The crownbased concept for Reptilia by definition omitted several Permian and Triassic taxa that, since their respective discoveries during the late 19th and early-mid 20th centuries, were regarded to be basal reptiles mesosaurids, millerettids, procolophonians, and pareiasaurs. Cladograms showing the progression of ideas concerning amniote phylogeny and nomenclature that are in line with traditional ideas for reptile interrelationships i.
The nomenclature shown employs a strict priority among the phylogenetic definitions for taxon names. Arrows indicate taxon names for clades. The Gauthier et al. Laurin and Reisz bestowed Olson's names Parareptilia and Eureptilia on the former and the latter groupings, respectively, as stem-based taxa.
The other major departure from the work of Gauthier et al. The Laurin and Reisz analysis supplanted that of Gauthier et al. It was slightly modified by Modesto who, in work stimulated by new data on mesosaur anatomy, placed mesosaurs back in a clade with millerettids, pareiasaurs, and procolophonids Fig. Because Parareptilia, as defined by Laurin and Reisz , was equated in both definition and content with Anapsida sensu Gauthier et al. Anapsida, which in traditional rank-based classifications grouped several early amniote groups together on the basis of a plesiomorphy the absence of temporal fenestrae , is an unfortunate name because it epitomizes a paraphyletic group to most students of early amniote phylogeny.
Reisz and Scott did use the term Anapsida for the clade of mesosaurs, millerettids, pareiasaurs, and procolophonids, but these authors did not include turtles in their analysis because of the ongoing controversy over turtle relationships. Reisz and Scott therefore appear to have associated the nomen Anapsida with the content of the group that was recognized by Modesto , rather than with the definition of the nomen created by Gauthier et al. Amniote phylogeny illustrating revised nomenclature assuming diapsid identity of Testudines as hypothesized by Zardoya and Meyer , Hedges and Poling , and Rieppel and Reisz , employing the revised phylogenetic definition for Reptilia suggested in the text.
Sources for skeletal reconstructions, from top to bottom: Dimetrodon from Romer and Price ; Procolophon from deBraga with permission from the National Research Council of Canada; Scutosaurus modified from Lee ; Mesosaurus original reconstruction by S.
- Micro-Segmented Flow: Applications in Chemistry and Biology.
- Recent Research on Wood and Wood-Based Materials. Current Japanese Materials Research!
- Arthropod Management in Vineyards:: Pests, Approaches, and Future Directions.
- A Brief History of Taxonomic Concepts for Reptilia!
- What is the Future of Hydropower?.
The amniote phylogenies of Gauthier et al. In traditional rank-based classifications, turtles were grouped with several early reptile groups within Anapsida Williston, ; Romer, ; Carroll, However, recent morphological and molecular studies suggest that turtles are instead diapsid reptiles, variously identified as lepidosauromorphs lizards, snakes, tuataras, and their fossil relatives; Rieppel and deBraga, ; deBraga and Rieppel, , or archosauromorphs crocodiles, birds, and their fossil relatives; Hedges and Poling, ; Kumazawa and Nishida, ; Zardoya and Meyer, , We will not go into further detail about these competing hypotheses for the diapsid affinities of turtles because they are beyond the scope of the present work, and the reader is referred to Zardoya and Meyer and Lee for detailed reviews and treatments of these hypotheses.
If the hypothesis that turtles are diapsid reptiles becomes the consensus view among systematists, it creates problems for the nomenclature of the reptilian side of the amniote tree. However, if a diapsid identity for turtles is accepted, the Gauthier et al. According to priority by date of first publication of a name, the former nomen should be recognized as the senior synonym, although the phylogenetic definition of Sauria has priority over that of Reptilia.
Questions of historical continuity aside, the definition for Reptilia must be emended because of its now circular construction. Unfortunately, definitions of Reptilia published subsequent to Gauthier et al. The deBraga and Rieppel definition is clearly a lapsus calami , because the content outlined in the definition is not consonant with the placement of Reptilia on their tree; their definition of Reptilia can be rejected for this reason.
Learn all about reptiles at Reptilia Indoor Zoo
The definition of Laurin and Reisz suffers the problem of internested specifiers if it is applied to phylogenies in which turtles are diapsids; this includes most recent studies of reptile interrelationships deBraga and Rieppel, ; Zardoya and Meyer, ; Hedges and Poling, ; Kumazawa and Nishida, ; Rieppel and Reisz, Lee is the only recent worker who espouses a parareptilian origin for turtles. Given the lack of consensus on the phylogenetic position of turtles, a phylogenetic definition of Reptilia that is not sensitive to the lability of this specifier taxon is clearly desirable.
A corollary problem caused by a diapsid origin for turtles is that Anapsida sensu Gauthier et al. Despite its phylogenetic reconception by Gauthier et al. Our reasoning with Anapsida does not necessarily translate to other taxonomic entities that have been recognized as paraphyletic in traditional classifications, such as Amphibia, Osteichthyes, and even Reptilia, because it is only with Anapsida that a single primitive morphological structure is strongly associated with the name.
Amniote phylogeny illustrating revised nomenclature assuming the diapsid identity of Testudines as hypothesized by Zardoya and Meyer , Hedges and Poling , and Rieppel and Reisz , and employing strict priority for phylogenetic definitions.http://argo-karaganda.kz/scripts/wiwybep/911.php
A Guide to Visiting Reptilia
The use of Reptilia here assumes the original crown group definition for the nomen Gauthier et al. The multiple phylogenetic definitions that have been devised for Reptilia Gauthier et al. These phylogenetic definitions, however, are not satisfactory for reasons discussed above. In addition, the view that Reptilia, like many familiar, established taxon names, should be defined as a crown group is not compulsory Bryant, ; Lee, ; Lee and Spencer, ; Sereno, ; see Anderson, and Laurin and Anderson, for a more detailed discussion.
The main objective for using crown-group definitions is that some workers believe such definitions are more stable than other phylogenetic definitions.
Paleontologists such as Lucas , Patterson , Lee , Lee and Spencer , and Benton have been particularly vocal in their opposition to crown-group definitions for well-known names because they appear to have the greatest impact on classifying fossil taxa. This situation is similar to the controversy surrounding the crown-group definition for Aves, in which many workers reject the idea that Archaeopteryx is not a bird because it falls outside of a crown-defined Aves Chatterjee, ; Chiappe, ; Padian, , ; but see Gauthier and de Queiroz, Evidence that most workers are loathe to accept a less inclusive Reptilia is illustrated in recent cladograms that portray the interrelationships of basal amniotes and assume diapsid affinities for turtles: most identify Reptilia as the sister group of Synapsida deBraga and Rieppel, : ; Modesto, : fig.
There are two cases in which Sauropsida is used in preference to, or interchangeably with, Reptilia. Benton , following his previous usage Benton, a , applied Sauropsida to the clade of Diapsida plus Testudines, making his Sauropsida a crown taxon Benton, b. In his concluding remarks, however, Benton : describes Sauropsida and Synapsida as sister taxa, a statement that is not consistent with the clade names in his figure. This statement is an error, because the figured phylogenies in both Benton b and Benton both use Sauropsida as a crown clade, whereas later Benton uses Sauropsida as a total group, as do Gauthier and Laurin and Reisz Benton's a , b , , use of the name Sauropsida changed as the concept of this group evolved in the literature personal communication, Lee used the names Sauropsida and Reptilia interchangeably in his paper; this appears to be due to the fact that Lee , following deBraga and Rieppel , excluded Mesosauridae from his consideration of reptilian phylogeny, which resulted in the content of the stem-based nomen Sauropsida being equated with that of the node-based Reptilia.
Under traditional rank-based nomenclature, Testudines would merely be considered sedis mutabilis , and it is doubtful that this uncertainty in the placement of turtles with respect to squamates, sphenodontians, and crocodiles would precipitate the growing perplexity of what is and what is not a reptile that has been wrought by Gauthier et al. Our concerns outlined here are not offered as a criticism of the theory and practice of PN, but as a critique of what time has revealed to be an improperly formed definition devised in the early stages of PN.
A Guide to Visiting Reptilia Indoor Zoo in Toronto
Watch our Cast at work in the nursery, our Closed Now. Suggested duration: hours. Improve This Listing. Thank you. TripAdvisor has been notified. This property is closed Report incorrect address Suggest edits. Do students receive discounted pricing? Yes No Unsure. Would you associate this place or activity with entertainment?
From Sea Turtles to Crocodiles
Does this place or activity allow service animals? Would you send a friend who is visiting for the first time to this place or activity? Do children receive discounted pricing? Is this a must-do if you are traveling with a big group greater than 5? Do seniors receive discounted pricing? Is this attraction a "must-see" location? Thanks for helping! Share another experience before you go.