an outgroup is used in order to:

*Correspondence to be sent to: Department of Geology and Geography, Georgia Southern University, P.O. Existing crocodyliform character sets include only brief state descriptions and are rarely figured. People can identify with ingroups and outgroups based on many factors, like ethnicity, gender, age, occupation, political affiliation, and even arbitrary criteria like being told theyre part of team A and someone else is a part of team B. 2001, 2003; Larsson and Sues 2007; Sereno and Larsson 2009; Young and Andrade 2009; Young et al. The cause of this discrepancy is unknown; however, the difference is minor and should not affect interpretations drawn from this study. Mahajangasuchus insignis possesses an internal choana entirely enclosed by the pterygoids, but in a manner unlike that of eusuchians (Turner and Buckley 2008). For example, this can help you understand why some people apply double standards by criticizing members of their outgroups for behaviors that they fully tolerate among members of their ingroup. , om another molecule such as pep, which is an example of, Plant can only grow under certain _ conditions. Oxford University Press is a department of the University of Oxford. This analysis resulted in 16 trees of length 1157 (CI = 0.310, RI = 0.692). The shortest trees obtained from these replicates were subjected to a final round of TBR branch swapping to ensure all minimum length trees were discovered. Strict consensus of 32 MPTs of length 1493 when outgroup taxa are excluded and the tree is rooted on Orthosuchus stormbergi (ordered analysis). Such is not the case in thalattosuchians, where the quadrate is expanded onto the braincase, but is not directly sutured to the laterosphenoid, basisphenoid, or pterygoid (Holliday and Witmer 2009; Jouve 2009; Fernndez et al. 6). When pholidosaurs and dyrosaurs were excluded from these analyses, thalattosuchians were recovered either as basal mesoeucrocodylians (when rooting on a protosuchian; Buckley and Brochu 1999), or sister to Crocodyliformes (when rooting on Gracilisuchus; Pol and Gasparini 2009). 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. Protosuchia is no longer monophyletic (which it cannot be if the tree is rooted on a single protosuchian taxon), and much resolution is lost among notosuchians. Thus, the evolution of the secondary palate is much more complicated than once thought, likely involving multiple gains and/or losses. 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. However, if thalattosuchians are the sister group to Crocodyliformes, this scenario is more complicated than it once seemed. Metriorhynchoid relationships are unchanged. Thus, a large amount of character and taxon information has not yet been included in previous efforts to address the longirostrine problem. This character state has no obvious functional relation to the possession of a long snout and thus seems good evidence of shared ancestry. This is important when it comes to dealing with the intergroup bias, since it means that people, including you, might not realize that they suffer from this bias, or might not realize the extent to which they suffer from it. Explanation: Share derived trait is the trait which is fou This is interpreted as a narrowed, but continuous mastoid antrum connecting the middle ear regions. out-group: [noun] a group that is distinct from one's own and so usually an object of hostility or dislike compare in-group 1. Three of these have been recovered as the sister taxon to Crocodyliformes in previous analyses (Junggarsuchus sloani, Clark et al. The unordered analysis yielded 566 MPTs (length = 1648; CI = 0.312; RI = 0.703). Its visibility relies on the availability of CT data, hemisected specimens, or specimens that are serendipitously broken to expose this passage. I made an effort to sample widely from all major Crocodylomorph groups. B) determine which character states are ancestral and which are derived. 2006). 2011; Pritchard et al. This major anatomical difference suggests these taxa should not be scored the same for this character, and that characters such as this might best be elaborated to include references to the individual bones forming the structure. 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. This conflict, at least superficially, mirrors that seen with Thalattosuchia and the longirostrine crocodyliformsan instance of strong, but conflicting, character support for multiple highly divergent topologies. Six sphenosuchian taxa were also sampled. I also demonstrate that expanding the outgroup sampling of previously published matrices results in the recovery of thalattosuchians as sister to Crocodyliformes. This issue was extensively discussed by Pol and Gasparini (2009), and they presented evidence demonstrating that many of these putative longirostrine characters are incompatible with biological dependence (eight of the 12 investigated). In the first cladistic matrices of Clark (Benton and Clark 1988; Clark 1994), Dyrosaurus and Pholidosaurus are coded as lacking a mastoid antrum that extends through the supraoccipital. Reanalysis of the data matrix of Turner and Buckley (2008) resulted in 120 MPTs of length 1122 (Fig. With this limited concept of social identity in mind, our argument is based on the following general assumptions: From these assumptions, some related theoretical principles can be derived: The basic hypothesis, then, is that pressures to evaluate ones own group positively through in-group/out-group comparisons lead social groups to attempt to differentiate themselves from each other, From An integrative theory of intergroup conflict (Tajfel & Turner, 1979). They need three things to survive _ _ _. In addition, various moderating factorscan influence the intergroup bias, for example when it comes to the way in which it manifests. 2004). 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). The outgroup is used as a point of comparison for the ingroup and specifically allows for the phylogeny to be rooted. Its addition will be an important test of the competing scenarios. 2002; Sereno et al. Brochu (2001) proposed that the inclusion of dyrosaurids and pholidosaurs in an analysis draws the thalattosuchians up the tree. D) decide which molecular data to use. Character 63 (continuity of mastoid antrum) was recoded as present in Rhabdognathus and Pholidosaurus based on evidence presented above. Analysis of the ordered data set excluding the noncrocodylomorph outgroups (Gracilisuchus and Postosuchus) and rooting on Hesperosuchus resulted in the same 42 MPTs (length 1632). The Impact of Outgroup Choice on the Phylogenetic Position of Thalattosuchia (Crocodylomorpha) and the Origin of Crocodyliformes", "Whole-genome analyses resolve early branches in the tree of life of modern birds", "Experimental systematics: sensitivity of cladistic methods to polarization and character ordering schemes", "Great ape genetic diversity and population history", "Using genomic data to unravel the root of the placental mammal phylogeny", "Evolution of the chordate body plan: New insights from phylogenetic analyses of deuterostome phyla", https://en.wikipedia.org/w/index.php?title=Outgroup_(cladistics)&oldid=1043888427, Creative Commons Attribution-ShareAlike License 4.0. 1position a). In all outgroup taxa (as well as basal crocodyliforms), the orbits are laterally oriented. If not, there is no expectation that the outgroup comply with the same norms or values as the ingroup. This character should only be scored for taxa in which the postorbital lies medial to the jugal. 2008; Sadleir and Makovicky 2008). Answer) Statement first. Accounting for the concept of ingroups and outgroups can be useful in various situations, such as when you want to understand and predict peoples behavior, including your own. a) A thalattosuchian - Peipehsuchus teleorhinus; b) A dyrosaurid - Dyrosaurus maghribensis (redrawn from Jouve et al. Thus, to perform a phylogenetic analysis, an outgroup is needed to determine which character states are ancestral and which are derived. The snout is a complex structure composed of several bones. C) determine which characteristics to include in our analysis. 161 of Sereno and Larsson 2009). This site is using cookies under cookie policy . This result occurs in spite of relatively dense sampling of other longirostrine taxa (four pholidosaurs, three dyrosaurs, Elosuchus, Stolokrosuchus, and Gavialis). In topologies in which thalattosuchians are allied with longirostrine crocodyliforms, thalattosuchians are inferred to have re-evolved this feature. 2; consistency index [CI] = 0.306, retention index [RI] = 0.710). d) partial braincase of Rhabdognathus keinensis (CNRST-SUNY 277) showing the greatly enlarged otic capsules and a narrow, but continuous tube through the supraoccipital here interpreted as the transverse passage of the mastoid antra. S1 available as Supplementary Material on Dryad at http://dx.doi.org/10.5061/dryad.00ss6). Theintergroup bias can influence cognition (i.e., thoughts about people, for example in the form of stereotyping), attitude(i.e., evaluation of people, for example in the form of prejudice), and behavior (i.e., actions toward people, for example in the form of discrimination). Many of these characters have been hypothesized to be correlated with longirostry (Benton and Clark 1988; Clark 1994; Jouve et al. Positive social identity is based to a large extent on favorable comparisons that can be made between the in-group and some relevant out-groups: the in-group must be perceived as positively differentiated or distinct from the relevant out-groups. In the context of ingroups and outgroups, a superordinate group (or superordinate category) is a social group within which social subgroups (or subordinate groups/categories) exist. Historically, thalattosuchians were interpreted as basal mesosuchians distantly related to crown-group Crocodylia (Klin 1955; Buffetaut 1982). westermani (Fernndez et al. Early mesozoic tetrapods, Two new basal crocodylomorph archosaurs from the Lower Jurassic and the monophyly of the Sphenosuchia, A Middle Jurassic sphenosuchian from China and the origin of the crocodylian skull, A new shartegosuchid crocodyliform from the Upper Jurassic Morrison Formation of western Colorado. (2010) for determining the minimum number of species necessary to represent a supraspecific taxon in an analysis of higher level relationships. What are potential points of disagreement between the groups? 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. To qualify as an outgroup, a taxon must satisfy the following two characteristics: Therefore, an appropriate outgroup must be unambiguously outside the clade of interest in the phylogenetic study. 2012). 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). Relationships in the rest of the tree are largely identical. In addition, given the wide range of criteria that people can use when distinguishing between ingroups and outgroups, there is a huge number of ingroups and outgroups that a person can reasonably identify. Social identity can be fluid, rather than stable, meaning that it can change based on factors like the environment a person is in. To assess the sensitivity of the topology to outgroup sampling, the analysis was also run in three permutations: Excluding the basal suchian Gracilisuchus (rooting on Postosuchus); excluding the noncrocodylomorph taxa Gracilisuchus and Postosuchus (rooting on Hesperosuchus agilis); and excluding all noncrocodyliforms and rooting on the protosuchian Orthosuchus stormbergi as in some published analyses (e.g., Sereno and Larsson 2009). a) A hemisected teleosaurid braincase (Teleosaurus macrocephalus; SMC J35177a) with a solid supraoccipital. Wu and Chatterjee (1993) state that Dibothrosuchus elaphros possesses a mastoid antrum extending through the supraoccipital, but whether the pneumatic recesses actually connect is unobservable in the holotype (J. Clark, pers. These various can co-occur and influence one another, but this doesnt always happen. 2013). com.). Many other examples of ingroups and outgroups exist, as people can develop their social identity based on various criteria, such as nationality, ethnicity, race, age, language, socioeconomic status (or social class), and occupation. 2013) and is fairly well supported (GC jackknife: 69). There are various types of intergroup biases, such as group-serving biases, which cause people to overvalue their ingroup (e.g., by attributing its failures to external factors and its successes to internal factors). industrial ecology uses such systems techniques as: 1. blood groups, such as the abo blood group, are based on the presence of, because atp does not have the highest phosphate transfer potential, this means that atp may be easily made by cells from adp and a phosphoryl group fr comm.). 2006. These codings have persisted in most matrices based directly on the original work of Clark (e.g., Turner and Buckley 2008; Pol et al. An ingroup is a social group that a person identifies as being a part of, based on factors like nationality, race, religion, socioeconomic status, or political affiliation. Traditionally the pholidosaurs and dyrosaurids were not thought to be closely related (Buffetaut 1982), however, all phylogenetic analyses including both groups have recovered them as a clade (e.g., Benton and Clark 1988; Clark 1994; Buckley and Brochu 1999; Wu et al. Parsimony jackknifing outperforms neighbor-joining, A metriorhynchid crocodyliform braincase from northern Chile, A reappraisal of the origin and basal radiation of the Osteichthyes, An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia, Combined support for the wholesale taxic atavism in Gavialine crocodylians, Improvements to resampling measures of group support, TNT, a free program for phylogenetic analysis, Rooting phylogenetic trees with distant outgroups: a case study from the commelinoid monocots, The epipterygoid of crocodyliforms and its significance for the evolution of the orbitotemporal region of eusuchians, Problems due to missing data in phylogenetic analyses including fossils: a critical review, Die Dinosaurier, Crocodiliden und Sauropterygier des norddeutschen Wealden, The crocodilian skull in historical perspective, Cranial osteology and phylogenetic relationships of, Parsimony, homology and the analysis of multistate characters, Terrestrial Mesonychia to aquatic Cetacea: transformation of the basicranium and evolution of hearing in whales, Are crocodiles really monophyletic?Evidence for subdivisions from sequence and morphological data, More about directed characters: a reply to Donoghue and Maddison. 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. 2003; McAliley et al. Addition of Postosuchus (scored for state 0), reconstructs state 0 as plesiomorphic. Thus, it could be interpreted that the expanded otic capsules of dyrosaurids caused the closure of the transverse canal connecting the mastoid antra. Analyses drawing thalattosuchians crownward link them with other long-snouted clades, suggesting that convergence related to snout shape may be confounding efforts to recover a phylogenetic signal. Addition of Gracilisuchus and Postosuchus causes major topological changes (Fig. To conduct a phylogenetic analysis, an outgroup is needed in order to: A) decide which characters are analogous and which are homologous. The state in dyrosaurids is slightly more difficult to interpret. Spaulding et al. These data sets were analyzed using unweighted parsimony in TNT v. 1.1 and the same search parameters described above. Mueller-Twe I.J. The difference in the number of MPTs is merely a result of the stricter collapsing rule employed here. Funding for this project was provided by the National Science Foundation (Doctoral Dissertation Improvement Grant DEB-1011097 to C. Brochu) and the University of Iowa Department of Geoscience. Strict consensus of 42 MPTs of length 1691 (CI = 0.306, RI = 0.710). Noncrocodyliform crocodylomorphs for which this character can be scored all possess a solid supraoccipital (Sphenosuchus acutusWalker 1990; Kayentasuchus walkeriClark and Sues 2002; Junggarsuchus sloaniClark et al. Ohio University 174 pp. Analyses of crocodyliform relationships should include outgroups sampled from closely related noncrocodyliform clades. 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. Araripesuchus becomes polyphyletic and, with the clade formed by Uruguaysuchus, Simosuchus, and Anatosuchus, forms a paraphyletic grade leading to neosuchians. When dyrosaurids and pholidosaurs are excluded from analyses, thalattosuchians move back toward the base of the tree (e.g., Buckley et al. This result occurs in spite of the inclusion of numerous nonthalattosuchian long-snouted taxa (dyrosaurids and pholidosaurs).

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