Potential Flood Boundary Implications of the Superfamily Djadochtatherioidea in the Extinct Multituberculata Order Relating to the K-Pg Boundary Using the PBDB

Defining the flood boundary in the fossil record has immense creation narrative value. Global extinction events are of major importance in identifying trends in the fossil record because a global flood would clearly cause major biotic turnover. Organisms which appear on either side of a major extinction event can reveal patterns of their dispersion given the event in question is the end of the flood. This idea ties closely to Arment’s Marsupial investigation, which demonstrates that Marsupials appear almost exclusively in Australia, suggesting a flood boundary after their appearance in the fossil record asserts that they migrate to the Ark and then immediately back to the same geographic location (2020). Studying other trends around proposed flood boundaries can reveal the unlikelihood of such chance migration. Multituberculates are an extinct group of mammals which appear on either side of the K-Pg boundary. Because the K-Pg is often proposed as the end flood boundary, the pattern of this order reveals the likelihood of this boundary given dispersion patterns. The Multituberculate order has several superfamilies, the focus of which is Djadochtatherioidea. There is a large amount of undetermined phylogeny in the order, lending the opportunity for analysis of past taxonomical decisions and some regrouping. The first goal was to locate the global occurrences of the Djadochtatherioidea superfamily in the Paleobiology Database. The papers corresponding to the database entries were then used to study the specimens, as well as local stratigraphy, to determine the validity of the specimen and the validity of its date relative to the K-Pg boundary. The largest family in Djadochtatherioidea is Eucosmodontidae, found throughout North America on both sides of the K-Pg, and in Mongolia. Flynn describes specimens from the Cretaceous of New Mexico which are morphologically identifiable as Eucosmodontidae (1986). Krause similarly describes specimens from the early Eocene of Wyoming (1982). Both papers demonstrate the presence of Eucosmodontidae and Djadochtatherioidea on both sides on the North American K-Pg boundary. Lesser specimens are found in Mongolia. Analysis of papers linked with the PBDB localities of Djadochtatherioidea in Mongolia reveal only Cretaceous specimens. These patterns demonstrate that the Djadochtatherioidea superfamily is likely a baramin which occupied modern North America and Mongolia and then dispersed to North America after the flood. The morphological similarity of the superfamily lends itself to single baramin classification, though more detailed work needs to be done to verify this. The global distribution of the superfamily does not prohibit the K-Pg boundary from being the end flood boundary, as it is entirely feasible that the kind existed in a few places, migrated to the ark, stayed morphologically similar during the flood years, and then the surviving individuals migrated to North America where some radiation occurred. Given the lack of return to Mongolia for the superfamily, it is not a case of unlikely remigration. It is important to note that this is a preliminary report on such findings. First, greater analysis of specimens must be done, Principal Component Analysis being the most obvious, before complete conclusions can be drawn on the baraminology of the group. Further, the order Multituberculata contains more superfamilies than Djadochtatherioidea, meaning more research regarding these other superfamilies must be conducted to determine if different patterns are present. However, this serves as a solid starting point regarding the Multituberculates and their story in the flood and its potential boundaries. Arment, C. 2020. To the Ark, and Back Again? Using the Marsupial Fossil Record to Investigate the Post-Flood Boundary. Answers Research Journal 13: 1-22. Flynn, L. 1986. Late Cretaceous Mammal Horizons from the San Juan Basin, New Mexico. American Museum Novitates no. 2845:1-30. Krause, D. 1982. Multituberculates from the Wasatchian Land-Mammal Age, Early Eocene, of Western North America. Journal of Paleontology 56, no. 2:271-294.