Systematic Originalism

On occasion, systematists feel the need to revise the taxonomy of various species, placing species into new genera, or lumping them in with other species in earlier-named genera. This is generally supported by phylogenetic analyses, but sometimes it involves an argument of differentiation based on physical differences, or mere opinion on the basis of particularly “important” features (generally autapomorphies). This can have several results, but the most common is that a systematist will erect a new genus for a “special” species formerly placed in another genus. Ignoring the question of what a genus is, we wonder what the answer to the question “What is the value of a generic assignment?”

I am of two minds: There is a principle of originalism, but also of “sense.” The former tends to be the most prevalent, although the second tends to rear its head time to time.

The principle of originalism goes: generic or specific assignments without systematic support for alternate hypotheses should be maintained. Under this philosophy, Brachiosaurus Riggs (1903) should include the type species (Brachiosaurus altithorax Riggs, 1913) as well as additional species, Brachiosaurus brancai Janensch, 1914, even if further analysis argued that Brachiosaurus brancai should be placed in a different genus (in this case, Giraffatitan Paul, 1988, see Taylor, 2009), so long as that analysis does not show either species to be closer to a species belonging to a different genus placed elsewhere phylogenetically.

Now, were brancai placed in a different position systematically, closer to another taxon than altithorax, this would change and Giraffatitan might be supported. The reason why this is untenable is because no analysis currently supports brancai as closer to another non-Brachiosaurus species; Taylor (2009) reasons this due to a large number of analyses lumping both species into a single unit for phylogenetic assessment, but also when used, only brancai is ever analyzed, but not altithorax. Testing this, Taylor found low support (if any) placing either species separately, but this is ambiguous according to Taylor. Nonetheless, until such an analysis is forthcoming with strong support, originalism dictates use of Brachiosaurus as the container for brancai, not Giraffatitan.

But on the other hand, there is the “sense” argument: Due to a taxonomic quirk known as priority and the large number of names present in the literature, some of them fairly obscure, names tend to get replaced from out of left field (as it were). This occurred with Diceratops Lull vide Hatcher (1905) [n1], which was later found to be preoccupied with an insect and renamed Nedoceratops (Ukrainsky, 2007); owing to its obscurity, the name was unknown when Mateus (2008) attempted to replace the name with Diceratus, a fact that Ukrainsky rejected using his own work in a more widely-known venue (Ukrainsky, 2009). This has led to a relatively convoluted synonymy list for whatever container holds hatcheri Lull vide Hatcher (1905), largely because the species has also been subsumed into Triceratops, sometimes as a synonym of one of its other species (see Scannella & Horner, 2010; Farke, 2011). Nonetheless, sense argues that we follow the latest assignment when all the details, even in the case of phylogenetic analysis, are applied. Farke (2011) argues against the opinion of Scannella and Horner (2010) by noting a large number of features that distinguish Nedoceratops hatcheri from Triceratops, thus permitting us to support the assignment.

This can have issues: What were to happen, say, if Nedoceratops does belong within a group of ceratopsians that includes Triceratops horridus the type species) and Triceratops prorsus? Originalism might imply we should then have to make a choice between retaining Nedoceratops and  distinguishing all species into their own equivalent “genus” containers (meaning a name would be coined to contain prorsus), or we subsume all others into Triceratops (as Scannella and Horner, 2010 chose), regardless of morphological ambiguity (Farke, 2011).

ICZN rules argue that the earliest valid name has priority over any other, and even a different animal named the same should have its name changed. This results in a need for a replacement, and Ivie et al. (2001) provided this in the case of Megapnosaurus. Noting that the name Syntarsus (for Syntarsus rhodesiensis Raath, 1969) was preoccupied by a beetle, Ivie et al. (2001) erected a new name for rhodiensis, creating Megapnosaurus rhodesiensis. However, the name they chose has problems. Ivie et al. coined the name from the Greek words μεγα (mega, “big”) and ‘απνοος (hapnoos, “non-breathing”), to create “big dead lizard.” Appearing in an entomology journal, this name was viewed as an affront on several levels, not just because of an entomologist renaming a taxon when the original author is generally granted this right (Mike Raath being available at the time), but also in the choice of terms, where a “big dead lizard” seems to be a fairly non-benign way to look at dinosaur-based paleontology. Ivie, in a message to the Dinosaur Mailing List, argued that it “was a joke,” but despite this, the name sticks.

The name has become something of a sore-spot. The general consensus has been to ignore it, and use Syntarsus anyways (e.g., Carranno & Sampson, 2008), or ignore it and use Coelophysis instead, to which Syntarsus has been synonymized by others (Bristowe and Raath, 2004; Bristowe et al., 2004; Yates, 2005). The latter has the benefit of ignoring the problem in a legitimate manner, but it runs afoul of the issue of originalism; the former runs afoul of ignoring the ICZN entirely, a subject of some oddity as both authors who did this also seek to employ the ICZN in arguing for the correct genus of Majungasaurus crenatissimus (Krause et al., 2007) or the type specimen of that species (Carrano et al., 2009).

Nonetheless, the issues above bear scrutiny. Should we employ a “sense” model, we apply a subjective, and fairly non-scientific “feels good” impression. The emotional concerns invested in such issues as Megapnosaurus (which I am generally opposed but argue is the appropriate name when rhodesiensis is considered non-Coelophysis), Giraffatitan (to which I am opposed to using for brancai so long as no good analysis is published supporting any reason the “genus” is useful systematically), or Nedoceratops (which analysis supports separately from other species, but which may get lost due to concerns over the “extent” of a genus) leads us down a metaphorical obstacle course, each decision placing a new barrier in the way and making the course longer and more complicated (just like any evolving rulebook).

I am hesitant about using Megapnosaurus, but I think that if we must treat Syntarsus rhodesiensis Raath, 1969 separately from Coelophysis, we should use it (I do not think the naming authors gave full faith to Mike Raath to re-select his own nomenclature). Certainly the same would be true of Giraffatitan, which has as its only current value the “sense” that brancai is different enough from altithorax to warrant it, a diagnostic separator that has yet to see the light of analysis.

Systematic originalism is, in the end, I think, the better of the two options, as it leaves less subjectivity to the taxonomist. It may require us swallowing our pride and perhaps our esteem, but we are ostensibly scientists, even if we occasionally practice art (nomenclature).

[n1] John Bell Hatcher is credited with the name Diceratops hatcheri by Richard Swan Lull largely due to Hatcher’s work intending to publish said genus. Hatcher, however, died before completing a monographic work, which O. C. Marsh began to finish before he, too, succumbed. Richard Swan Lull, in better health, completed the monograph, then separately published the portion of the work erecting a new taxon, using Hatcher’s intended name, and renaming the species in Hatcher’s honor. The “vide” appellation is an honorific from Lull in reference to the work both men labored on.

Bristowe, A. & Raath, M. A. 2004. A juvenile coelophysoid skull from the Early Jurassic of Zimbabwe, and the synonymy of Coelophysis and Syntarsus. Palaeontologia Africana 40:31-41.
Bristowe, A., Parrott, A., Hack, J., Pencharz, M. & Raath, M. A. 2004. A non-destructive investigation of the skull of the small theropod dinosaur, Coelophysis rhodesiensis, using CT scans and rapid prototyping. Palaeontologia Africana 40:159-163.
Carrano, M. T. & Sampson, S. D. 2008. The phylogeny of Ceratosauria (Dinosauria : Theropoda). Journal of Systematic Palaeontology 6(2):183-236.
Carrano, M. T., Krause, D. W., O’Connor, P. M. & Sampson, S. D. 2009. Case 3487. Megalosaurus crenatissimus Depéret, 1896 (currently Majungasaurus crenatissimus; Dinosauria, Theropoda): proposed replacement of the holotype by a neotype. Bulletin of Zoological Nomenclature 66(3):261-264.
Farke, A. A. 2011. Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A. PLoS ONE 6(1):e16196. doi:10.1371/journal.pone.0016196.
Hatcher, J. B. 1905. Two new Ceratopsia from the Laramie of Converse County, Wyoming. American Journal of Science (Series 4) 20:413–422.
Ivie, M. A., Ślipiński, S. A. & Węgrzynowicz, P. 2001. Generic homonyms in the Colydiinae (Coleoptera: Zopheridae). Insecta Mudi 15:63-64.
Janensch, W. 1914. Übersicht über der Wirbeltierfauna der Tendaguru-Schichten nebst einer kurzen Charakterisierung der neu aufgeführten Arten von Sauropoden [Overview of the vertebrate fauna of the Tendaguru deposits together with a short characterisation of the many species of Sauropoda]. Archiv für Biontologie 3:81–110.
Krause, D. W., Sampson, S. D., Carrano, M. T. & O’Connor, P. M. 2007. Overview of the history of discovery, taxonomy, phylogeny, and biogeography of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. In Sampson & Krause (eds.) Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology, Society of Vertebrate Paleontology Memoir 8:1-20.
Mateus, O. 2008. Two ornithischian dinosaurs renamed: Microceratops Bohlin 1953 and Diceratops Lull 1905. Journal of Paleontology 82(2):423.
Paul, G. S. 1988. The brachiosaur giants of the Morrison and Tendaguru with a description of a new subgenus, Giraffatitan, and a comparison of the world’s largest dinosaurs. Hunteria 2(3):1-14.
Raath, M. 1969. A new coelurosaurian dinosaur from the Forest Sandstone of Rhodesia. Arnoldia, Rhodesia 4(28):1-25.
Riggs, E. S. 1903. Brachiosaurus altithorax, the largest known dinosaur. American Journal of Science (series 4) 15(88):299-306.
Scannella, J. & Horner, J. R. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4):1157–1168.
Taylor, M. P. 2009. A Re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropod) and its generic separation from Giraffatitan brancai (Janensh 1914). Journal of Vertebrate Paleontology 29(3):787-806.
Ukrainsky, A. S. 2007. A new replacement name for Diceratops Lull, 1905 (Reptilia: Ornithischia: Ceratopsidae). Zoosystematica Rossica 16(2):292.
Ukrainsky, A. S. 2009. Synonymy of the genera Nedoceratops Ukrainsky, 2007 and Diceratus Mateus, 2008 (Reptilia: Ornithischia: Ceratopidae). Paleontological Journal 43(1):116.
Yates, A. M. 2005. A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods. Palaeontologia Africana 41:105-122.

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10 Responses to Systematic Originalism

  1. The emotional concerns invested in such issues as Megapnosaurus (which I am generally opposed but argue is the appropriate name when rhodesiensis is considered non-Coelophysis)

    I certainly don’t like how Megapnosaurus arose as a name, but I see it as valid and, like you, has to be used for non-Coelophysis former “Syntarsus.” The big question is what to do about “M.kayentakatae ’til it gets its own name…!

  2. I don’t understand how you justify keeping brancai in Brachiosaurus only until it is shown to be phylogenetically separated. This assumes their sister group relationship to be the null hypothesis, but Taylor demonstrated the characters used by Janensch all have broader disatributions. Surely a lack of specific relationships to any other species is the null hypothesis, so using distinct genera (when available) is best for species unless we have particular evidence of their relationship to one another. By continuing to use Brachiosaurus brancai, you’re supporting the hypothesis brancai is sister to altithorax, which has no support AFAIK.

    • This is actually irrelevant. I argued that the nomenclature should not be changed because it is not useful nor descriptive of any hypothesis, not because brancai in Brachiosaurus is more useful or descriptive of an hypothesis. This is [as I wrote] as if I were to “remove” prorsus from Triceratops into a new generic label, only the taxon were to go nowhere in “phylogenetic space.”

      If we want to argue the null hypothesis, then we need to have a null hypothesis, but for me, that is that no species are nomenclaturally differentiated. When we name a new species or separate a species from a genus, the reasoning should be sound on a lot of levels, but I think phylogenetically is just one of several. Taylor’s reasoning is primarily founded on the numerical value of differentiable features, but this serves no useful function without a phylogenetic analysis to back it up. As neither taxon (as yet) is closer to another differentiated “genus” (which I am sure will be the case once the taxa that make up Brachiosauridae or other non-titanosaurian titanisauriforms are treated to more extensive phylogenetic analysis, at the hopefully specimen or species-level).

      • Mike Taylor says:

        I reject the notion that nomenclatural judgements should be dictated only by numerical phylogenetic analysis. However much we might wish we could find a purely objective basis for our nomenclature, the simple truth is that we can’t. All our decisions are informed by taste, experience and precedent, and pretending otherwise is fantasy.

    • I should clarify one thing:

      It is true that keeping the taxa together has no support, but also true that separating the taxa has no support. In this case, I use the originalism argument and support Janensch’s assignment (although apparently regarding the other species he erected without comment) as a nomenclatural issue — not a phylogenetic one.

      I repeat, for yours or Mike’s ears, that this is nomenclatural and not phylogenetic, and I make NO assumptions on the relationships of the taxa.

  3. I can’t agree with your values then. “Originalism” has no value for me in science, and I believe all hierarchical nomenclature/taxonomy should be phylogenetic.

    • I’m using the principle I outlined in the post to discriminate situations when no scientific or phylogenetic hypothesis is superior, or even present. Arguments previous standing were “taste” or “art” reasons, such as naming a new genus because the author thinks it is distinct enough, not justified through discriminate analysis.

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