Paper Abstracts

Dinosauria baraminology

N.A. Doran, N. Hartman, A. Sanderson

Discipline: Geology

Abstract: The Dinosauria pose both interesting and challenging questions. One question is whether new dinosaur discoveries are closing morphospatial gaps between dinosaurian groups, revealing continuous morphological fossil series, such as between coelurosaurians and avialans. These questions underscore the importance of systematics for resolving correct group memberships, including tools for visualizing morphospatial relationships. Baraminic distance correlation (BDC), three-dimensional multidimensional scaling (MDS), and a new method to baraminic studies - principal component analysis (PCA) - were applied to 18 character matrices from 2004. The data included saurischian and ornithischian dinosaur groups including (1) basal Saurischia, (2) Ceratosauria (including Coelophysidae), (3) basal Tetanurae (both maniraptoriform and non-maniraptoriform), (4) Tyrannosauroidea, (5) Prosauropoda, (6) Sauropoda, and Maniraptoriformes (7) Ornithomimosauria, Dromaeosauridae, and Troodontidae (single matrix, including a few Alvarezsauridae), (8) Therizinosauroidea, and (9) Oviraptorosauria. The ornithischians included (10) basal Thyreophora, (11) Stegosauria, (12) Ankylosauria, (13) basal Ornithopoda, (14) basal Iguanodontia, (15) Hadrosauridae, (16) Pachycephalosauria, (17) Ceratopsia, and (18) Ceratopsidae. From the 2004 data we report seven tentative holobaramins, five apobaramins, and five groups with unclear associations. PCA identified several clear morphospatial divisions within taxonomic groups not identified by BDC. For comparison 19 newer datasets (from 2009 to 2018) were analyzed using PCA alone. The results revealed a substantially clearer picture since only 2004. Dinosaur groups included morphospatial clusters and series of taxa. Holobaramins were revealed mainly as closely-spaced morphospatial series of taxa. Some series were additionally stratomorphic. Assuming holobaramin are discontinuity-bounded morphospatial series of taxa, we estimate 36 potential holobaramin within the newer data. PCA revealed that bird-dinosaur morphospatial relationships vary by dataset. Maniraptorans likely contain two branching morphoseries, connected at the base by dromaeosaurs and avialans. The morphoseries are functional/ecological, rather than evolutionary. Multivariate analysis offers the potential to improve our understanding of baramins, discontinuity, and provide a new perspective on questions in creation systematics such as bird-dinosaur relationships.