Analysis of the ordered data set excluding the eight outgroup taxa and rooted instead on the protosuchian Orthosuchus resulted in 32 MPTs (Fig. an outgroup is used in order to: decide which characteristics are However, construction of the postorbital bar differs radically between thalattosuchians and pholidosaurs/dyrosaurids. However, a specimen of Rhabdognathus keinensis (CNRST-SUNY 277) shows a narrow tube extending through the supraoccipital in the dorsal roof of the braincase (Fig. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. Pairs of birds were observed for 2 hour periods. Thus, to perform a phylogenetic analysis, an outgroup is needed to determine which character states are ancestral and which are derived. Outgroup (cladistics) - Wikipedia 2013) generally root their topologies on Gracilisuchus stipanicicorum and include two sphenosuchian crocodylomorphs: Terrestrisuchus gracilis and Dibothrosuchus elaphros (it should be noted that these analyses greatly reduced the number of sampled outgroups originally present in Clark 1994). Legitimate differences in interpretation of morphology exist, but many differences in character state coding in current published literature are likely due to ambiguity in character state descriptions. The basal suchian Gracilisuchus was used to root the tree based on its position in the broad scale analysis of Archosauria by Nesbitt (2011). The analysis also recovers a monophyletic Notosuchia (including a monophyletic Peirosauridae in some MPTs), Atoposauridae, Goniopholididae, Dyrosauridae, and Pholidosauridaeclades commonly recovered in other published analyses. While some analyses of archosaur relationships have recovered Gracilisuchus as a close relative of Crocodylomorpha (e.g., Brusatte et al. Some of the other characters uniting thalattosuchians and pholidosaurs/dyrosaurids in the analysis of Pol and Gasparini (2009) may be misleading due to vagueness of character state descriptions failing to accurately reflect anatomy. The goal of phylogenetic analysis may be to recover structure within the ingroup (Maddison et al. An elongate tubular rostrum is another such feature (char. Outgroup sampling was increased from previous analyses with the intent of better characterizing the distribution of character states in noncrocodyliforms. PDF CODE REVISER USE ONLY RULE-MAKING ORDER - Washington Department of Fish Optimization of the palatal development character (char. 6). Many of these characters have been hypothesized to be correlated with longirostry (Benton and Clark 1988; Clark 1994; Jouve et al. Another example of an ingroup and an outgroup appears in the case of a college student, who views other students from the same major as belonging to their ingroup, and views students from other majors as belonging to their outgroup. Group membership is used to derive meaning about oneself, and, consequently, motivates identification with positively valued groups and promotes behaviours that advance the group's interest [].Intergroup contact makes salient one's group membership and highlights the existence of both an ingroup and an outgroup [2,3,4,5,6].Such contact can, however be considered stressful . The analysis presented here (Fig. See answer Advertisement VTDK248 To perform a phylogenetic analysis, an outgroup is needed to determine which character states are ancestral and which are derived. 2009; Young et al. Later works no longer dismissed the longirostrine clade, but it has remained suspect for three primary reasons (Pol and Gasparini 2009). The basal suchian Gracilisuchus was used to root the tree based on its position in the broad scale analysis of Archosauria by Nesbitt (2011) . In cladistics or phylogenetics, an outgroup[1] is a more distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroup, the set of organisms under study, and is distinct from sociological outgroups. 163) suggests that the mesosuchian palate is primitive for Crocodyliformes, and an extensive secondary palate has been lost at least twice (Fig. All phylogenetic data sets are available as Supplementary Material on Dryad at http://dx.doi.org/10.5061/dryad.00ss6. In thalattosuchians, the snout is composed of the maxillae and premaxillae, whereas in pholidosaurs and dyrosaurids, the nasals extend the length of the snout, forming the dorsal portion (Fig. Some analyses recover thalattosuchians as sister to Crocodyiformes (Fig. For example, its possible for intergroup discrimination to occur due to ingroup favoritism, even in the absence of outgroup antagonism. Twenty unambiguous and nine ambiguous synapomorphies support the exclusion of Thalattosuchia from Crocodyliformes (Table 1). What's in an Outgroup? The Impact of Outgroup Choice on the b, c) natural endocast of the ear canal region from Pholidosaurus meyeri (HMN R. 2066) in anterior (b) and dorsal (c) views showing a large and fully connected mastoid antrum. 2009). I made an effort to sample widely from all major Crocodylomorph groups. comm.). Two separate analyses were run. So, the correct option is B. 2006; Jouve 2009; Pol and Gasparini 2009; Turner and Sertich 2010; Andrade et al. If the relationships between these groups are not well known, the effects of outgroup sampling should be assessed by investigating changes to ingroup topology under different outgroup sampling schemes. While I have no evidence to contradict previous codings for Sarcosuchus, Dyrosaurus, or Terminonaris, given the presence of a fully connected mastoid antrum in both Pholidosaurus and Rhabdognathus, two relatively distantly related taxa, it seems likely that pholidosaurs and dyrosaurs do possess a continuous mastoid antrum as in all other crocodyliform taxa for which this character can be scored. However, in looking for this similarity, one should not resort to gross similarity in shape or size. Box 8149, Statesboro, GA 30460, USA E-mail: Search for other works by this author on: A new neosuchian crocodyliform from the lower Cretaceous (late Aptian) twin mountains formation of north-central texas, Rooting with multiple outgroups: consensus versus parsimony, Archosaur phylogeny and the relationships of the Crocodylia, The phylogeny and classification of the tetrapods, Morphology, fossils, divergence timing, and the phylogenetic relationships of, Crocodylian snouts in space and time: phylogenetic approaches toward adaptive radiation, A dyrosaurid crocodyliform braincase from Mali, A species-level supertree of Crocodyliformes, Representing supraspecific taxa in higher-level phylogenetic analyses: guidelines for palaeontologists, The higher-level phylogeny of Archosauria, An enigmatic new crocodile from the upper Cretaceous of Madagascar, A pug-nosed crocodyliform from the Late Cretaceous of Madagascar, Radiation volutive, palocologie et biogographie des crocodiliens msosuchiens, The structural consequences of skull flattening in crocodilians, Functional morphology in vertebrate paleontology. Protosuchians have a modest secondary palate, with the internal choana bordered anteriorly by the maxillae. Outgroup sampling is a central issue in phylogenetic analysis. 2011; Young et al. Jackknife support was calculated in TNT using 1000 replicates with the probability of independent character removal set at 0.37 (e1; as recommended in Farris et al. Character 41 describes the orientation of the orbit. westermani (Fernndez et al. However, observation of this character in fossil taxa is often difficult, due to infilling by sediment or poor preservation. 2009), and Sarcosuchus imperator and Terminonaris robusta have also been coded as lacking this feature. 2011; Pritchard et al. For comparative purposes, both Postosuchus and Gracilisuchus were added to the data set of Sereno and Larsson (2009). Very distantly related taxa are expected to share fewer relevant character states with the ingroup and have had greater time to accumulate homoplasy. Strict consensus tree showing ACCTRAN optimization of the secondary palate character. outgroup A species or higher taxon used in systematics for comparison with a group of closely related species or taxa in order to assess whether particular characters shared by the group members are derived (see apomorphy) or ancestral (see plesiomorphy ). Many of the features of the braincase linking Junggarsuchus and Almadasuchus with crocodyliforms are not preserved in Kayentasuchus, thus additional fossil material may be required to resolve this portion of the tree with any confidence. 2006) or as the sister group to Crocodyliformes (e.g., Pol and Gasparini 2009). For example, a religious person might view members of their religion as being a part of their ingroup, while viewing members of other religions as being a part of their outgroup. 2006; Larsson and Sues 2007; Jouve 2009; Young and Andrade 2009; Turner and Sertich 2010; Bronzati et al. (3) Character information supporting the noncrocodyliform affinities of thalattosuchians is present, but the lack of proper outgroup sampling forces the reconstruction of plesiomorphic character states as synapomorphies for Thalattosuchia. Strict consensus of 42 MPTs of length 1691 (CI = 0.306, RI = 0.710). 2003; Larsson and Sues 2007; Sereno and Larsson 2009). Language links are at the top of the page across from the title. Thus, the evolution of the secondary palate is much more complicated than once thought, likely involving multiple gains and/or losses. If there is agreement between the groups about the representation of the superordinate group and the subgroups relative prototypicality, the implied value differentiation will be regarded as legitimate and will be non-conflictual. Secondarily aquatic lineages have arisen in nearly every major tetrapod group. [3] Prior to the advent of the term, various other terms were used by evolutionary biologists, including "exgroup", "related group", and "outside groups". This result is very similar to the topology recovered by Turner and Sertich (2010). This search resulted in 2038 MPTs of length 1121. The following are specific examples of ways people categorize their ingroups and outgroups, which also illustrate how this type of social identity can influence peoples thoughts and actions: Accordingly, the concept of ingroups and outgroups is associated with various common phenomena, including racism, sexism, nationalism, patriotism, tribalism, collective narcissism, groupthink, and a polarized us vs. them mentality. As such, in the following article you will learn more about this aspect of social identity, understand the psychology behind it, and see what you can do to account for it in practice. 2001, 2003; Brochu et al. 24 of Turner and Buckley 2008), whereas no noncrocodyliform crocodylomorphs possess this morphology (though Almadasuchus comes close). This site is using cookies under cookie policy . 2002; Sereno et al. Its addition will be an important test of the competing scenarios. Is platyrostral really more similar to tubular than to broad oreinirostral? This analysis recovers a monophyletic Protosuchia, an uncommon result found in some previous analyses (e.g., Wu et al. Absence of a prearticular is an apomorphic feature of mesoeucrocodylians, but a prearticular is present in noncrocodyliform crocodylomorphs, protosuchians, and thalattosuchians. individualistic or collectivist), and the age and self-esteem of group members. The phylogenetic data set was analyzed in TNT v1.1 (Goloboff et al. If it is present in Dibothrosuchus this is the result of convergence. Another potentially important feature involves the groove on the lateral surface of the squamosal for external ear valve musculature attachment (char. Social identity can be fluid, rather than stable, meaning that it can change based on factors like the environment a person is in. Thus, a large amount of character and taxon information has not yet been included in previous efforts to address the longirostrine problem. In topologies in which thalattosuchians are allied with longirostrine crocodyliforms, thalattosuchians are inferred to have re-evolved this feature. For example, one study found that negational categorization leads to increased outgroup derogation, compared to affirmational categorization. Some taxa (e.g., Dakosaurus) possess relatively short, robust snouts. Dufeau D.L. A key framework thats used to explain why and how people distinguish between ingroups and outgroups issocial identity theory, whichexplains this phenomenon as follows: We can conceptualize a group as a collection of individuals who perceive themselves to be members of the same social category, share some emotional involvement in this common definition of themselves, and achieve some degree of social consensus about the evaluation of their group and of their membership of it, Social groups provide their members with an identification of themselves in social terms. Choosing a closely related outgroup relative to the ingroup is more useful when looking at subtle differences, while choosing an unduly distant outgroup can result in mistaking convergent evolution for a direct evolutionary relationship due to a common ancestor. Another synapomorphy of the longirostrine clade is the transversely flattened postorbital bar (char. It must be related to the ingroup, closely enough for meaningful comparisons to the ingroup. Reanalysis of the Turner and Buckley matrix with character 3 treated as unordered greatly reduces resolution in the strict consensus, but has no effect on the longirostrine clade. 1994, 1997, 2001; Jouve et al. An outgroup that is nested within the ingroup will, when used to root the phylogeny, result in incorrect conclusions about phylogenetic relationships and trait evolution. When Thalattosuchia is a part of the longirostrine clade, dorsally directed orbits are optimized as the primitive state, with laterally directed orbits arising secondarily in metriorhynchoids and S. brevior. However, exclusion of the four potentially nonindependent characters in their data set did not change their topology and thalattosuchians and pholidosaurs/dyrosaurids remained a clade. Clark J.M. For Permissions, please email: journals.permissions@oup.com, DNA Sequences Are as Useful as Protein Sequences for Inferring Deep Phylogenies, Resolving marinefreshwater transitions by diatoms through a fog of gene tree discordance, A k-mer-based approach for phylogenetic classification of taxa in environmental genomic data, Speciation in Coastal Basins Driven by Staggered Headwater Captures: Dispersal of a Species Complex, Leporinus bahiensis, as Revealed by Genome-wide SNP Data, Inferring historical introgression with deep learning, About the Society of Systematic Biologists, Receive exclusive offers and updates from Oxford Academic, Copyright 2023 Society of Systematic Biologists. I will also test the effects of outgroup sampling on the phylogenetic relationships of crocodylomorphs in general, and the position of Thalattosuchia in particular, through modification to the outgroup sampling scheme of this and previously published data sets. The three contentious longirostrine groups are all found in marine environments suggesting they share similar ecological/functional pressures. 2008; Sadleir and Makovicky 2008). To reduce the intergroup bias, you can use various combinations of the following techniques: When deciding which techniques to use and how to use them, you should consider both personal and situational factors that pertain to the situation, like: Its important to note that people generally tend to attribute more biased intergroup beliefs to others than to themselves. The rauisuchid (sensu Nesbitt 2011) Postosuchus kirkpatricki was included for two primary reasons. Both analyses incorporated additive characters, and these were retained as such. 2013). Smith (1994) suggested that sampling the two closest successive sister groups is the ideal scheme for choosing outgroups. Some of these groups will be more important to them than others, though which are more important can vary under different circumstances, for example if the question of membership in a certain group is particularly salient in a certain situation. Previous work has demonstrated that outgroup sampling can have a great effect on ingroup relationships, particularly for labile clades (e.g., Spaulding et al. 3 of Turner and Buckley 2008; similar to char. While there are no guarantees that a particular outgroup taxon or number of outgroups will yield the correct ingroup topology (Nixon and Carpenter 1993), it seems prudent to sample numerous outgroup taxa especially where large-scale relationships between clades remain an active question. D) decide which molecular data to use. The exclusion of Thalattosuchia from Crocodyliformes is supported by 13 unambiguous and five ambiguous synapomorphies (Table 1). Six sphenosuchian taxa were also sampled. Crocodylians and their relatives (Crocodylomorpha) are no exception to this pattern. Araripesuchus becomes polyphyletic and, with the clade formed by Uruguaysuchus, Simosuchus, and Anatosuchus, forms a paraphyletic grade leading to neosuchians. [7] However, the optimal level of relatedness of the outgroup to the ingroup depends on the depth of phylogenetic analysis. In the second, multistate characters were treated as unordered to avoid making a priori assumptions about the process of evolution (though whether treating such characters as unordered involves better justified assumptions has been questioned; e.g., Lipscomb 1992; Slowinski 1993).
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