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Keywords:

  • Archaeopteryx;
  • baraminology;
  • classic multidimensional scaling;
  • Coelurosauria;
  • creationism;
  • creation science;
  • Theropoda

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

It is important to demonstrate evolutionary principles in such a way that they cannot be countered by creation science. One such way is to use creation science itself to demonstrate evolutionary principles. Some creation scientists use classic multidimensional scaling (CMDS) to quantify and visualize morphological gaps or continuity between taxa, accepting gaps as evidence of independent creation and accepting continuity as evidence of genetic relatedness. Here, I apply CMDS to a phylogenetic analysis of coelurosaurian dinosaurs and show that it reveals morphological continuity between Archaeopteryx, other early birds, and a wide range of nonavian coelurosaurs. Creation scientists who use CMDS must therefore accept that these animals are genetically related. Other uses of CMDS for evolutionary biologists include the identification of taxa with much missing evolutionary history and the tracing of the progressive filling of morphological gaps in the fossil record through successive years of discovery.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

Morphological continuity between related extinct taxa from successive time periods is one of the main lines of evidence supporting evolutionary theory. For cases in which such continuity is interrupted by significant morphological disparity between taxa, a gap is said to exist in the fossil record (e.g. Lee, 1993; Strahler, 1999; Norell & Clarke, 2001). A gap is also said to exist if the fossil record of a taxon is interrupted by a long stratigraphic hiatus (e.g. Li et al., 2009; Choiniere et al., 2010). The focus of this article is on morphological gaps rather than stratigraphic gaps, and henceforth in this article the term ‘gap’ refers to a morphological gap.

It would be instructive to be able to visualize and quantify morphological gaps in the fossil record. This would serve three useful functions. First, it could be used to determine which taxa have more missing evolutionary history than others, as determined by the presence of larger gaps separating such taxa from others. Second, a comparison between the gaps in the fossil record as it was known at different points in human history could serve as a gauge of progress in the filling of such gaps during successive periods of discovery. Third, visual and quantitative verification of the absence of gaps between major taxa could serve as confirmation of the evolutionary relatedness of those taxa. The use of a gap visualization and quantification method endorsed by creation science (the creationist discipline in which extrabiblical evidence is sought for a literal interpretation of the biblical book of Genesis) would be especially useful for this third purpose. This is because, if such a method demonstrated morphological continuity in a fossil series, creation scientists would be obliged to either accept that by their own logic the included taxa are evolutionarily related or that their own logic is internally inconsistent. Here, I show that gaps in the fossil record can indeed be visualized towards these ends using a method derived from the literature of creation science.

For those readers who question the value of addressing creation science in a biological journal, I must insist that it is imperative to do so. A huge percentage of the North American and European populations hold creationist viewpoints (Mazur, 2005; Miller et al., 2006), and political opposition to the teaching of evolutionary theory in public schools is strong (Berkman et al., 2008; Branch & Scott, 2009). We can turn a blind eye to this only at great risk. Practitioners of creation science are the ones who mould and hone creationist arguments, and it is towards their claims that the defence of evolutionary biology is best directed. Evolutionary biologists have a long history of using the findings of mainstream science to counter the claims of creation science (e.g. Isaak, 2007 and references therein). Such defence would be especially unassailable if creation science itself were to be used to defend evolutionary theory, because such a study would put creation science in the ironic position of having to reject its own previous research or accept the results of the new study. Here, I show that this can be carried out and provide an example involving the evolutionary transition from coelurosaurian dinosaurs to basal birds.

The method used here is derived from the literature of baraminology, a branch of creation science in which organisms are classified according to a creationist framework. According to baraminologists, each ‘kind’ (baramin) of organism was created independently and has subsequently undergone diversification. The current level of diversity recognized within each baramin often meets or exceeds the family level of mainstream taxonomy (e.g. Siegler, 1978; Wood, 2006b). For example, all members of the cat family, Felidae, are considered to represent a single baramin (Robinson & Cavanaugh, 1998b), the various species of which are all descendants of the originally created, ancestral felid. Baraminologists consider two species members of the same baramin if they can interbreed, but often this information is not available. Baraminologists therefore usually employ measures of morphological and/or molecular continuity, viewing morphological gaps between taxa as evidence that the taxa were created separately. In 1998, the baraminologists Robinson & Cavanaugh (1998a) introduced the concept of morphological distance between taxa to identify morphological gaps. Cavanaugh subsequently developed ANOPA (analysis of patterns), a method in which a matrix of character states – e.g. a data matrix such as is typically used in a phylogenetic analysis of fossil taxa – is used to project an n-dimensional pattern of morphological similarity (where n is the number of morphological characters) onto three-dimensional space (Cavanaugh & Sternberg, 2004). In the resulting three-dimensional scatter plot, spatial gaps between the dots that represent taxa correspond to morphological gaps between those taxa. In 2005, the baraminologist Todd Charles Wood introduced another method to convert a matrix of character states into a visualization of taxa in character space: classic multidimensional scaling (CMDS). Whereas ANOPA calculates three-dimensional coordinates directly from the matrix of character states, CMDS first converts the matrix of character states into a matrix of morphological distances between taxa and then calculates three-dimensional coordinates from that matrix (Wood, 2005a). Using ANOPA and CMDS, baraminologists have conducted several searches for morphological gaps in extant and fossil taxa. Such studies have identified significant morphological gaps between major groups of extant and extinct cetaceans (Cavanaugh & Sternberg, 2005; Mace & Wood, 2005; Wood, 2005a), between Arthropoda and Annelida, and between Arthropoda and Mollusca (Cavanaugh, 2006). Other such studies have verified morphological continuity, indicating inclusion in a single baramin, among the major groups within the sunflower tribe Heliantheae (Cavanaugh & Wood, 2002; Wood, 2005a), between Hippopotamidae and the extinct genera Merycopotamus and Libycosaurus (Wood, 2006a), between finned archeocetes and early mysticetes (Wood, 2007), and – contrary to decades of previous creationist claims (e.g. Cousins, 1971; Gish, 1995) – between the fossil mammal Hyracotherium and the members of Equidae (the horse family) (Wood & Cavanaugh, 2003; Wood, 2005a). Two such studies that included dozens of extant plant and animal taxa have verified that, in general, morphological gaps separate extant families from each other, but morphological continuity exists within families (Wood, 2005b, 2008a).

It should be noted that ANOPA and CMDS are not strictly creationist techniques. They are mathematical techniques, and mathematics has no creed. Both can be applied outside baraminology. Indeed, ANOPA was introduced in a secular biological study that was published in a mainstream biological journal (Cavanaugh & Sternberg, 2005) and was coauthored by Richard Sternberg, who is not a creationist. Nonetheless, because these techniques are standard for baraminology, results obtained from their use should be accepted by baraminologists. Here, I take advantage of this using CMDS to quantify and visualize morphological distances between members of the dinosaurian taxon Coelurosauria, including basal birds such as Archaeopteryx. This group of organisms is of particular interest to evolutionary biologists because it includes taxa that are hypothesized to reveal an evolutionary transition from nonavian dinosaurs to birds. The group is of interest to creation scientists for the same reason. The taxon Archaeopteryx is of particular interest to creation scientists because evolutionary biologists have long asserted that it is an example of an evolutionarily transitional form, and creation scientists have long argued against that assertion (e.g. Morris, 1974; Gish, 1995; Lutz, 1995; DeYoung, 2000).

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

Phylogenetic analysis

The character matrix that I chose for CMDS (Appendices S1 and S2 in the Supporting Information) is a modified version of one from a recent phylogenetic analysis of Coelurosauria (Senter, 2007). After that analysis was published, new personal observations of museum specimens engendered substantial changes to the data for several OTUs (operational taxonomic units), and I added newly discovered taxa and made other improvements and updates to the matrix. These are described and justified in Appendix S3 in the Supporting Information. Because of the large number of changes and the addition of new taxa, I reran the phylogenetic analysis for this study. The present version of the matrix includes 89 OTUs and 364 characters.

For the phylogenetic analysis, I used PAUP 4.0 for Windows (Swofford, 2001) to run a heuristic search using 1000 random addition-sequence replicates. To find the decay index of each clade, I used the same software after insertion of the appropriate command line, which was created using the program MacClade 3.08a (Maddison & Maddison, 1999).

Multidimensional scaling

I analyzed coelurosaurian character space using CMDS for five versions of the data matrix described earlier. The five versions are hereafter called the 1920 matrix, the 1980 matrix, the 1990 matrix, the 2000 matrix and the 2009 matrix. Each matrix includes all 364 characters and includes only the taxa for which a description or illustration of at least one nearly complete skeleton was published in primary scientific literature during or before the year after which the matrix is named. For example, the 1920 matrix includes only the taxa for which nearly complete skeletons were described or illustrated in primary scientific literature by 1920. The 1920 matrix includes six OTUs, the 1980 matrix includes 12 OTUs, the 1990 matrix includes 14 OTUs, the 2000 matrix includes 21 OTUs, and the 2009 matrix includes 33 OTUs.

For the analysis, I used the program BDISTMDS (Wood, 2008b), which is freely available for use at http://www.bryancore.edu. I modified each of the five versions of the matrix so as to maximize the information content [number of characters × number of operational taxonomic units (OTUs)] that would be utilized by BDISTMDS for the analysis. In its calculation of three-dimensional coordinates for the visualization, BDISTMDS ignores any OTU with a taxic relevance (ratio of the number of characters with known states to the total number of characters) below 0.66 and any character with a relevance cut-off (ratio of the number of OTUs in which the state is known, to the total number of OTUs) below that set by the researcher, in this case 0.95, the recommended value (Robinson & Cavanaugh, 1998a,b). Therefore, to maximize the information content used by BDISTMDS for the visualization, it was necessary to maximize the number of OTUs with taxic relevance of ≥ 0.66 and the number of characters with relevance cut-offs of ≥ 0.95. This was accomplished as follows. First, I ran the matrix through BDISTMDS to find the taxic relevance of each OTU, and I deleted any OTU with a taxic relevance of < 0.4 (this raised the relevance cut-off of each character by eliminating taxa with much missing data). Next, I deleted any character for which the state is unknown in at least 50% of the remaining OTUs (this raised the number of OTUs with a taxic relevance of ≥ 0.66). I ran the resulting version of the matrix through BDISTMDS, which revealed the new taxic relevance of each OTU, and I deleted any OTU with a taxic relevance of 0.66 (these taxa would have been ignored by BDISTMDS anyway, and this further increased the number of characters with a relevance cut-off of ≥ 0.95). Finally, the matrix was rerun through BDISTMDS to obtain the coordinates for three-dimensional visualization. Experimentation revealed that this method of progressive culling of less-informative OTUs and characters did indeed increase the number of OTUs and the number of characters that were used by BDISTMDS to obtain the coordinates, thereby maximizing the utilized information content. The number of characters used by BDISTMDS was 141 for the 1920 matrix, 88 for the 1980 matrix, 82 for the 1990 matrix, 90 for the 2000 matrix and 40 for the 2009 matrix. The characters retained by BDISTMDS for the analysis come from an anatomically broad sample of bodily regions. An exception is the braincase, which is little known for most taxa; accordingly, BDISTMDS ignored most braincase characters.

Some of the OTUS in the matrices are composites, combining data from two or more OTUs that were found to be sister taxa by the phylogenetic analysis. Characters that differ among constituent OTUs of each composite OTU are treated as multistate characters. The composite OTUs were created to maximize the information content utilized by BDISTMDS. In each case, each constituent OTU has a taxic relevance of < 0.66, but the taxic relevance of the composite OTU meets or exceeds 0.66. The 2009 matrix contains three composite OTUs: Erliansaurus Neimongosaurus Segnosaurus Erlikosaurus + Therizinosaurus, Incisivosaurus Protarchaeopteryx and Epidendrosaurus Epidexipteryx. For this version of the matrix, I also created five additional composite OTUs that were not used in the final BDISTMDS analysis because even as composites the taxic relevance of each is < 0.66. They are Tanycolagreus Coelurus, Chirostenotes Elmisaurus Hagryphus, Sinornithoides Saurornithoides junior + Saurornithoides mongoliensis Troodon, Unenlagia Buitreraptor Rahonavis and Dromaeosaurus Achillobator + Utahraptor. The 1980, 1990 and 2000 matrices each have one composite OTU: Segnosaurus Erlikosaurus Therizinosaurus; Erliansaurus and Neimongosaurus were added to this OTU for the 2009 matrix to increase its information content, because all their known skeletons have many missing parts, and Erliansaurus and Neimongosaurus were not known until after 2000 (Zhang et al., 2001; Xu et al., 2002a).

For each version of the matrix, I employed JMP software (SAS Institute, Inc., 2009) to produce a visualization of coelurosaurian character space in the form of a three-dimensional scatter plot, using the coordinates produced by BDISTMDS. In the visualization, coelurosaurian character space is represented by a cube, and each OTU is represented by a dot within the cube.

I used the output from BDISTMDS and JMP to test several hypotheses, each with its own predictions, that relate to the issues raised in the Introduction. For any given pair of clusters of OTUs in the scatter plot, the hypothesis that they are separated by a morphological gap predicts that the morphological distance between the two clusters exceeds the morphological distances within each cluster (e.g. the hypothesis that Dromaeosauridae and Troodontidae are separated by a morphological gap predicts that the distance between Dromaeosauridae and Troodontidae on the scatter plot exceeds distances within Dromaeosauridae and within Troodontidae). For any given year, the hypothesis that progress has been made in the filling of gaps predicts that at least some gaps that were present in preceding years are bridged in the year in question. For any given suprageneric taxon, the hypothesis that much of its evolutionary history is missing predicts that the taxon is separated by a gap from its nearest neighbours on the CMDS scatter plot.

Because the method employed here is derived from the literature of creation science, it is only fair to acknowledge that within the creationist paradigm, the hypothesis that any given cluster of OTUs on the scatter plot constitutes an independent ‘created kind’ (baramin) makes the same prediction as the last hypothesis in the preceding paragraph. Likewise, within the creationist paradigm, the hypothesis that any two clusters of OTUs on the scatter plot are part of the same baramin predicts that the distance between the two clusters does not exceed distances within each cluster (note that this is the opposite prediction from that of the first hypothesis in the preceding paragraph).

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

Phylogenetic analysis

Phylogenetic analysis yielded 216 most parsimonious trees with 1285 steps. The strict consensus tree is shown in Fig. 1. For these trees, the consistency index (ci) is 0.35, the homoplasy index (hi) is 0.65, the retention index (rc) is 0.77, and the rescaled consistency index is 0.27.

image

Figure 1.  Strict consensus tree found by phylogenetic analysis, with decay index for each clade.

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The topology of the consensus tree produced here (Fig. 1) is identical to that produced by the previous version of the matrix (Senter, 2007) except in three spots. First, Adasaurus is found to be the sister taxon to Tsaagan + (Velociraptor + Dromaeosaurinae), whereas the results of the previous analysis placed it in an unresolved trichotomy with Tsaagan and Velociraptor + Dromaeosaurinae. Second, Caudipteryx is found to be the sister taxon to Avimimus + [Microvenator + (Oviraptoridae)], whereas the results of the previous analysis placed it in an unresolved trichotomy with Microvenator and Oviraptoridae. Third, Rinchenia and the unnamed oviraptorid IGM 100/42 form a polytomy with Ingeniinae and Citipati + (Hagryphus Elmisaurus Chirostenotes), whereas those two OTUs had previously clustered with the latter clade. The phylogenetic positions of the newly added taxa, as found by this analysis, agree with those found by previous analyses (Chiappe et al., 1998; Kobayashi & Lü, 2003; Göhlich & Chiappe, 2006; Xu et al., 2006; Zhang et al., 2008; Sereno et al., 2009), except that here Scipionyx samniticus joins a clade of European compsognathids, whereas it was previously placed outside Compsognathidae (Holtz et al., 2004), and the positions of the troodontids Anchiornis and Sinovenator are reversed with respect to their previously found positions (Hu et al., 2009). Synapomorphy lists for each clade are given in Appendix S4 in the Supporting Information.

Decay indices, for the most part, resemble their counterparts from the previous analysis (Senter, 2007). A major exception is the series of decay indices along the spine of the cladogram, which are smaller than their previous counterparts (Fig. 1).

Classic multidimensional scaling

Morphological distances between taxa and three-dimensional coordinates for the visualizations are given in Tables S1–S10 of the Online Supporting Information. Taxa in the 1920 matrix are separated by large morphological distances (Fig. 2). The smallest morphological distance between taxa is that between Compsognathus and Ornitholestes (0.121), foreshadowing a close clustering between those two taxa in the matrices from subsequent years.

imageimage

Figure 2.  Scatter plots produced by MDS analysis of coelurosaurian character states, in ‘top’ (left) and oblique ‘front’ (right) views, showing taxa known from relatively complete skeletons in the years 1920, 1980, 1990, 2000 and 2009.

For taxa in the 1980 matrix (Fig. 2), a small morphological distance (0.091) exists only between Compsognathus and Ornitholestes, among the two outgroups (0.080), among members of Ornithomimidae (0.000–0.023) and among members of Dromaeosauridae (0.057). Larger distances (0.146–0.466), indicating gaps, exist between these four clusters, so that no morphological continuity is apparent between clusters.

The situation is similar for the taxa in the 1990 matrix (Fig. 2). Small distances (< 0.100) exist among members of each family (Ornithomimidae, Oviraptoridae, Dromaeosauridae), among the outgroups, and between Compsognathus and Ornitholestes, whereas larger distances (0.159–0.500), indicating gaps, persist between the five clusters.

In the 2000 matrix (Fig. 2), the gap between Archaeopteryx and the dromaeosaurids from previous matrices (Deinonychus and Velociraptor) is bridged by newly discovered, more birdlike dromaeosaurids (Sinornithosaurus and Microraptor). Archaeopteryx is separated from the dromaeosaurids by distances of 0.213 (from Sinornithosaurus) to 0.279 (from Deinonychus) and from the bird Confuciusornis by a distance of 0.211. Distances within Dromaeosauridae range in size from 0.146 (Deinonychus and Velociraptor) to 0.218 (Deinonychus and Microraptor). There is therefore less morphological distance between Archaeopteryx and the nearest dromaeosaurid in the scatter plot than there is within Dromaeosauridae. Other clusters, spanned by distances of no more than 0.190, include those among Ornitholestes and Compsognathidae, among members of Ornithomimidae, and among members of Oviraptoridae. Distances between Caudipteryx and members of Oviraptoridae (0.189–0. 213) are less than those within Dromaeosauridae but are still substantial. Large gaps, mostly > 0.300, remain between clusters.

The 2009 matrix (Fig. 2) reflects the new discoveries of several taxa that bridge gaps between formerly separated clusters. With the addition of the basal tyrannosauroid Guanlong and the basal compsognathids Huaxiagnathus, a coherent cluster (hereafter called the Tyrannosaur Cluster) is formed by Tyrannosauroidea, Compsognathidae and Ornitholestes. A second cluster, hereafter called the Birdlike Cluster, includes basal birds and the birdlike taxa Dromaeosauridae, Troodontidae, Epidendrosaurus + Epidexipteryx, Protarchaeopteryx Incisivosaurus and Falcarius. Between the least-separated members of the two clusters (Guanlong in the Tyrannosaur Cluster and Falcarius in the Birdlike Cluster) is a gap of only 0.135, which is smaller than the span of either cluster (0.143 for the Tyrannosaur Cluster, and 0.263 for the Birdlike Cluster). Distances of ≥ 0.200, indicating gaps, continue to isolate Oviraptoridae, Caudipteryx, Shuvuuia, Ornithomimidae and Therizinosauridae from all other taxa.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

Tyrannosauroidea, Compsognathidae and Ornitholestes form a morphologically continuous group. Basal birds (Archaeopteryx, Confuciusornis, Sapeornis) are part of a morphologically continuous group that also includes Dromaeosauridae, Troodontidae, Epidendrosaurus Epidexipteryx, Protarchaeopteryx Incisivosaurus and Falcarius. Therefore, baraminologists must consider the members of each group to be genetically related. The distance between the two groups is also small enough that within the baraminological paradigm both groups are arguably genetically related to each other.

There has been a progressive filling of gaps in the coelurosaurian fossil record over the years, but most gaps were still unfilled even as late as 2000. Most of the filling of gaps in the coelurosaur fossil record with specimens complete enough for inclusion in a BDSITMDS analysis has taken place since 2000.

Persistently missing evolutionary history is greatest for Ornithomimosauria, Oviraptorosauria, Alvarezsauridae and Therizinosauroidea. It is smallest for Tyrannosauroidea, Compsognathidae, Deinonychosauria and basal Avialae.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

In creationist literature, there is a longstanding tendency to dispute that basal birds such as Archaeopteryx exhibit morphological continuity with nonavian dinosaurs. Whereas most creationist authors treat Archaeopteryx as fully avian (e.g. Morris, 1974; Gish, 1995; DeYoung, 2000), at least one has opined that it is neither bird nor reptile but is its own kind of organism, ‘more like a lone obelisk than a connection between two sides of a gulf’ (Lutz, 1995). However, the results of this study show that such positions are untenable, even within the paradigm of creation science. As shown here, according to one of their own statistical measures, baraminologists must consider Archaeopteryx and other basal birds – including the more typically birdlike Confuciusornis and Sapeornis– the genetic relatives of dromaeosaurids and other birdlike coelurosaurs, and possibly even compsognathid and tyrannosauroids. It is also noteworthy that Archaeopteryx is morphologically intermediate between Dromaeosauridae + Troodontidae on the one hand and Confuciusornis Sapeornis on the other, as shown by its intermediate position on the 2000 and 2009 scatter plots (Fig. 2). Its status as a transitional form between the two groups is therefore supported by the results of this study.

Even so, it is important to note that, as shown in Fig. 2, morphological continuity between nonavian coelurosaurs and basal birds was not established until the discoveries of the most recent two decades. Before then, creationist insistence that the known fossil record did not contain a continuous morphological sequence from nonavian coelurosaurs to birds (e.g. Gish, 1995; Lutz, 1995) was correct. Until the most recent two decades, large enough morphological gaps existed between major coelurosaurian groups for a case to be made that each was a separate ‘created kind’. In fact, such a claim can still be made for Oviraptoridae, Ornithomimosauria and Therizinosauridae. As shown in Fig. 1, basal members of the latter three groups are known, but CMDS will not demonstrate that they bridge the relevant gaps until more complete skeletons are found. Likewise, fragmentary basal oviraptorosaur taxa are known (Fig. 1), but CMDS will not demonstrate that they bridge the gaps between Protarchaeopteryx + Incisivosaurus and Caudipteryx, and between Caudipteryx and Oviraptoridae, until they are known from more complete skeletons. Even so, creation scientists should note that the results of this study reveal a recent explosion of gap-filling, and it may only be a matter of a few years before these gaps are also filled. It would therefore be premature to announce that Oviraptoridae, Ornithomimosauria and Therizinosauridae are independent ‘created kinds’. It is also possible that the gap between Shuvuuia and other coelurosaurs is filled by a recently discovered basal alvarezsauroid (Choiniere et al., 2010); the new alvarezsauroid was not included in this analysis because its discovery was announced too late for its inclusion here.

A morphological difference exists between every pair of taxa, but the transition from coelurosaurian dinosaurs to birds is no longer represented by a large enough morphological gap to support a claim of separate creation. Coelurosauria is not the only clade in which significant morphological gaps have recently been filled by new fossil discoveries. The same has recently occurred with basal chordates (Shu et al., 1999; Mallatt & Chen, 2003), basal bony fishes (Zhu et al., 2009), the fish-to-tetrapod series (Boisvert, 2005; Daeschler et al., 2006; Long et al., 2006), basal turtles (Li et al., 2008), Mesozoic mammals (Ji et al., 1999, 2002; Luo et al., 2003) and other taxa. Gaps are expected in the fossil record, because fossilization is rare. Given this, the recent explosion in the filling of fossil gaps should give creationists pause, for any such gap-filling is a serious challenge to creation science. However, to test whether such gaps have been filled well enough to prevent rejoinder from creation science, evolutionary biologists must apply ANOPA, CMDS or related methods to phylogenetic data matrices of the taxa in question.

Those who accept macroevolution should note that while that acceptance is supported by the results of this study, substantial evolution within a ‘created kind’ is allowed within the creationist paradigm. Creation scientists have long agreed that the taxonomic limits of the ‘created kind’ can transcend the familial level (e.g. Siegler, 1978; Wood, 2006b). A real evolutionary relationship between basal birds and nonavian dinosaurs is therefore insufficient to convince a creationist that today’s birds are genetically related to nonavian dinosaurs. To adjust the creationist paradigm to be consistent with the results of this study, one has only to acknowledge the existence of convergent evolution. Within that paradigm, the Birdlike Cluster can be interpreted as a set of birdlike animals in which convergent evolution caused some members (Archaeopteryx, Confuciusornis, Sapeornis) to evolve a more typically birdlike body than others. Likewise, the Tyrannosaur Cluster can be interpreted as a set of animals in which convergent evolution caused some to evolve the morphology and large size typical of theropods of the taxon Carnosauria (represented by Allosaurus and Sinraptor among the outgroups used here). Alternately, the two clusters can be considered a single ‘created kind’ in which convergent evolution produced some birdlike and some carnosaur-like members. The diversity present in the Tyrannosaur Cluster + Birdlike Cluster may at first seem too great to have sprung from a single created pair of individual dinosaurs, but acceptance of the genetic relatedness of the few dozen species in less than a dozen families within this pair of clusters should be no problem for one who accepts even greater diversity within the limits of a ‘created kind’. For example, such diversity within a ‘created kind’ is compatible with the hypothesis of Steven Robinson (2000) that all of the approximately 2700 extant species of snake in 18 families (Greene, 1997) have evolved from the single pair of snakes that disembarked from Noah’s Ark.

It is noteworthy that bifurcating trajectories are visible in the 2009 scatter plot in a number of places (Fig. 2). Within Dromaeosauridae, the sequence Velociraptor[RIGHTWARDS ARROW]Deinonychus and the sequence Sinornithosaurus[RIGHTWARDS ARROW]Microraptor extend in different directions from Bambiraptor, which is at the apex of the ‘V’. Another bifurcation is present within the Tyrannosaur Cluster, with Guanlong Ornitholestes at its apex and with Gorgosaurus[RIGHTWARDS ARROW]Tyrannosaurus leading in one direction and Huaxiagnathus[RIGHTWARDS ARROW] (Sinosauropteryx Compsognathus) leading in another direction. Baraminologists recognize that a trajectory of dots within a CMDS or ANOPA scatter plot represents morphological evolution within a lineage (Wood & Cavanaugh, 2003; Wood, 2005a,b), in which case bifurcating trajectories must represent speciation. It is also noteworthy that these bifurcating patterns correspond reasonably well to the bifurcations on the cladogram in Fig. 1, with the more basal members of each group closer to the origin of each scatter plot bifurcation.

An interesting consequence of this study is that its results are compatible with the creationist assertion that all carnivorous animals evolved from originally herbivorous ancestors, but only if creationists accept that two oft-repeated creationist assertions are erroneous: (i) that members of the Tyrannosaur and Birdlike Clusters, including Archaeopteryx, are not evolutionarily related and (ii) that ziphodont (laterally compressed, pointed at the tip and somewhat recurved) teeth in theropods do not indicate carnivory. According to the young-earth creationist paradigm (in which all kinds of organism were created within one week about 6000 years ago), animals cannot have been created carnivorous, because there was no death before the Curse (the result of the sin of the first humans), and the evolution of carnivory was an effect of the Curse on the world (e.g. Smith, 1970; McIntosh & Hodge, 2006). The isolation of Ornithomimosauria, Therizinosauridae and Oviraptorosauria – which have specializations for herbivory (Smith, 1992; Barrett, 2005; Zanno et al., 2009) – on the scatter plot is consistent with the hypothesis that they were originally herbivorous. The presence of herbivorous taxa within the Birdlike Cluster is also consistent with the hypothesis of original herbivory for the group. Falcarius, Protarchaeopteryx and Incisivosaurus exhibit herbivorous dental specializations (Xu et al., 2002b; Kirkland et al., 2005); members of Avialae lack ziphodont teeth (Howgate, 1984; Hou et al., 1995; Zhou & Zhang, 2003; Zhang et al., 2008); and the large denticles on the teeth of some troodontids are compatible with herbivory (Holtz et al., 1998). Palaeontologists have long interpreted the presence of ziphodont teeth in Dromaeosauridae, Tyrannosauridae and Compsognathidae as evidence of carnivory (Osborn, 1906; Ostrom, 1969, 1978). If creationists wish to interpret these animals as carnivores that evolved from herbivores as a result of the Curse, then they must do the same. This will entail reversal of the creationist claim (in support of original herbivory) that such teeth could belong to herbivores (e.g. Ham, 2001; McIntosh & Hodge, 2006), along with a cessation of the depiction of tyrannosaurs and other ziphodont theropods eating watermelons and other fruit (Ham, 2001; McIntosh & Hodge, 2006) – depictions that, to creationists’ credit, are not common.

As one who himself accepts the evolution of all organisms from a common ancestor, I say these things not to advance the creationist cause but to point out that this study alone will not cause the extinction of creationist sentiment. It will, however, oblige creation scientists to take two major steps in the right direction: (i) the acknowledgement that by the logic of baraminology, Archaeopteryx and at least two other genera of feathered animal that are even more birdlike are evolutionarily related to dromaeosaurids and a plethora of other birdlike dinosaurs and (ii) the acknowledgement that theropods with ziphodont teeth were carnivores. These steps, if studies such as this accumulate, have the potential to lead down a slippery slope with a paradigm shift at its end. Creation science has already reversed its position on several evolutionary topics, and many (but not all) creation scientists now accept the existence of natural selection (Brand & Gibson, 1993), beneficial mutations (Wood, 2002), the reality of the geologic column (Tyler & Coffin, 2006), the lack of geologic evidence that Phanerozoic sedimentary strata were deposited by the Genesis Flood (Robinson, 1998; Tyler, 2006), and the evolutionary relatedness of members of the fossil ‘horse series’ (Wood & Cavanaugh, 2003; Wood, 2005a,b), all of which were typically disputed by creation scientists in decades past (e.g. Morris, 1972; Gish, 1995). With each reversal of position, resistance to evolutionary theory lessens. Studies such as this can only further that process. It is therefore my hope that this study inspires others to make it merely the first of many of its kind.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

David Cavanaugh deserves a heap of thanks for help with issues related to ANOPA, CMDS, and BDISTMDS; for a constructive review of an earlier draft of this manuscript; and for exemplifying a collegial spirit of cooperation that transcends ideological differences. Michel Laurin and an anonymous reviewer deserve thanks for helpful reviews of this manuscript. The following people deserve thanks for granting access to specimens for the phylogenetic study: Peter Makovicky (cast of the holotype of Buitreraptor gonzalezorum), Jeff Bartlett (Utahraptor ostrommaysorum holotype), Daniel Brinkman (Yale Peabody Museum specimens), Pat Holroyd, Kevin Padian (Dilophosaurus wetherilli), Carl Mehling and Mark Norell (specimens at the American Museum of Natural History).

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  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information
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Supporting Information

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Conclusions
  7. Discussion
  8. Acknowledgments
  9. References
  10. Supporting Information

Appendix S1 Character List for Phylogenetic Analysis.

Appendix S2 Phylogenetic Data Matrix.

Appendix S3 Changes to Character List and Matrix, and Potentiallly Controversial Scorings.

Appendix S4 Synapomorphy List.

Table S1 Morphological distances between taxa as found by CMDS analysis of the 1920 matrix.

Table S2 Three-dimensional coordinates of the CMDS visualization of the 1920 matrix. Number and color on left refer to the label and color of each taxon’s point in the scatter plot (Fig. 2).

Table S3 Morphological distances between taxa as found by CMDS analysis of the 1980 matrix.

Table S4 Three-dimensional coordinates of the CMDS visualization of the 1980 matrix. Number and color on left refer to the label and color of each taxon’s point in the scatter plot (Fig. 2). Note that closely related ingroups are given the same color, and non-coelurosaurian ougroups are black.

Table S5 Morphological distances between taxa as found by CMDS analysis of the 1990 matrix.

Table S6 Three-dimensional coordinates of the CMDS visualization of the 1990 matrix. Number and color on left refer to the label and color of each taxon’s point in the scatter plot (Fig. 2). Note that closely related ingroups are given the same color, and non-coelurosaurian ougroups are black.

Table S7 Morphological distances between taxa as found by CMDS analysis of the 2000 matrix.

Table S8 Three-dimensional coordinates of the CMDS visualization of the 2000 matrix. Number and color on left refer to the label and color of each taxon’s point in the scatter plot (Fig. 2). Note that closely related ingroups are given the same color, and non-coelurosaurian ougroups are black.

Table S9 Morphological distances between taxa as found by CMDS analysis of the 2009 matrix.

Table S10 Three-dimensional coordinates of the CMDS visualization of the 2009 matrix. Number and color on left refer to the label and color of each taxon’s point in the scatter plot (Fig. 2). Note that closely related ingroups are given the same color, and non-coelurosaurian ougroups are black.

Figure S1 Tooth inclination in Bambiraptor feinbergorum and Deinonychus antirrhopus, showing evidence that the strong inclination of some teeth is a taphonomic artifact.

Figure S2 Illustration of selected character states and potentially controversial scorings.

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