Preliminary assessment of insect herbivory across the Cretaceous-Tertiary boundary: Major extinction and minimum rebound

Abstract

Forty-nine insect damage types morphologically characterize plant-insect associations spanning a 136 m composite boundary interval from the uppermost Cretaceous Hell Creek Formation to the lowest Paleocene Fort Union Formation. The time duration of this interval is •2.2 m.y., 1.4 m.y. of which is latest Cretaceous. These data originate from 80 localities from the Williston Basin of southwestern North Dakota and are allocated to four assemblage zones consisting of 385 megafloral morphotypes of bryophytes, ferns, conifers, cycads, Ginkgo, monocots, and 333 dicots. All 49 foliar damage types were produced by external foliage feeding, mining, galling, and piercing and sucking insects, each of which was assigned one of the following host specificity levels: generalized, intermediate, or specialized. A distinctive pattern emerged when these damage types were plotted stratigraphically: of the 22 damage types that survive the Cretaceous-Tertiary boundary (K-T), 55% are generalized; of the 15 damage types that are extinguished immediately below the boundary, all are specialized or intermediate, as are the 12 damage types that disappear in stepped fashion somewhat before the boundary. Within this interval only two damage types are unique to the Fort Union Formation, occurring during the lowest Paleocene. These data indicate that highly and moderately specialized associations were preferentially culled at the K-T boundary, disproportionately enriching early Paleocene floras in generalized herbivores as dominant colonizers. These data are local, and the Signor-Lipps effect may partially obscure the true pattern, thus restricting extrapolation to the Western Interior of North America. Nevertheless, (1) the selective extinction of specialist herbivores at the boundary, (2) the absence of significant evidence for immigrant colonization, (3) the prolonged occurrence of species-depauperate floras during the Paleocene, and (4) the high percentage of last occurrences at and not before the boundary, despite the Signor-Lipps effect, suggest a role for end-Cretaceous abiotic perturbation and consequent biotic response in the evolution of modem plant and insect associations.

Odonatan endophytic oviposition from the Eocene of Patagonia: The ichnogenusPaleoovoidusand implications for behavioral stasis

“…Moreover, the traces documented by Labandeira (2002a), from the middle Eocene Republic Flora of eastern Washington, USA, show similar patterns that were defined as separated, equalsized, lenticular scars, arranged in semicircular arcs. Scars from the latest Cretaceous Hell Creek Formation of North Dakota, USA, show similar morphologies to the ones described here but lack a clear pattern of arrangement (Labandeira et al, 2002). Recently, Vasilenko (2007Vasilenko ( , 2008 described specimens on the floating leaves of Quereuxia possessing elongate oviposition scars of 0.75 to 0.…”

Generalist flowers and phytophagous beetles in two tropical canopy trees: resources for multitudes

“…This damage is similar in pattern and detail to some extant beetle-cycad associations, and attribution of the plant host to a modern taxon of cycads was described as "remarkably similar" (Klavins & al., 2005). Additionally, cycad foliage contains sporadic damage from external foliage feeders during the later Mesozoic that may be consistent with some modern erotylid and aulacosceline leaf beetle herbivory (Labandeira & al., 2002;pers. observ.).…”

Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary

“…The K-Pg mass extinction was a severe, global, and rapid extinction coinciding with an extraterrestrial impact (11) and resulted in major extinctions in terrestrial ecosystems. Nonavian dinosaurs and pterosaurs became extinct, and major extinctions also occurred among mammals, reptiles, insects, and plants (8,(12)(13)(14). It would be remarkable if birds survived the K-Pg event unscathed; however, the hypothesis of an avian mass extinction at the K-Pg boundary (3-5) has been debated.…”