[17] During a Mount Holyoke College field trip to Death Valley, California, McMenamin and his co-authors found evidence indicating that the Proterozoic shelly fossil Qinella survived the Proterozoic-Cambrian boundary.
[19] In his 2019 article 'Cambrian Chordates and Vetulicolians', McMenamin described Shenzianyuloma yunnanense, a new genus and species of Vetulicolia interpreted as bearing myotome cones, a notochord, and gut diverticula in its posterior section.
[20] In an attempt to explain the unprecedented and rapid spread of vegetation over dry land surfaces during the middle Paleozoic, Mark and Dianna McMenamin proposed the Hypersea Theory.
Joining with Lynn Margulis and the Russian symbiogeneticists, McMenamin has argued that symbiogenesis theory is important as one means of addressing the gap in our understanding of macroevolutionary change in conventional Neodarwinian terms.
[25] The Phoenician state of Carthage minted gold staters in 350 BC bearing a pattern in the reverse exergue of the coins, which McMenamin interpreted as a map of the Mediterranean with the Americas shown to the west across the Atlantic.
[30][31] PZ Myers believes that a much simpler explanation is that the rows of vertebral discs may be a result of the ichthyosaurs having fallen to one side or the other after death and rotting in that position, while Ryosuke Motani, a paleontologist at the University of California, Davis, has alternately proposed that the bones may have been moved together by ocean currents because of their circular shape.
[33] Mark and Dianna McMenamin presented new evidence favoring the existence of the hypothesized Triassic kraken on October 31, 2013 at the Geological Society of America annual meeting in Denver, Colorado.
Fastovsky stated that the most likely scenario was one in which, once the tendons and ligaments holding the vertebrae together are gone, the vertebral column "sort of starts to fall over almost like a row of dominoes" with the most likely configuration for that to be the assemblage found.