It's garbage
1st - In regards to the so called Asteroid who cares what happened after the K-T event since there is increasing evidence that the Chicxulub crater predates the end-Cretaceous mass extinction by about 300,000 years. (More links here and here)
2nd, Dinoflagellates. Brinkhuis and Zachariasse (1988)record no accelerated rates of extinction across the K-T boundary in Tunisia.
So let me get this straight, The Sky was darkened which allowed the benthic foraminifera to move into a new area, Yet in that area Dinoflagellates who depend on sunlight and would be devastated in 6 months without it survived with no ill effects in the same area.
3rd, This is just one small area where there could be many reasons for a localized cooling effect. By focusing on one tiny area and ignoring the rest of world the scientist are being disingenuous at best.
In the rest of the world, Micro fossils show a different story, For example
a) Diatoms. The K-T event did not much affect the diatoms. Harwood (1988), based on studies from Seymour Island, eastern Antarctic Peninsula, the first to record siliceous microfossil assemblages across a K-T boundary sequence, notes that diatom survivorship across the K-T boundary was above 90 percent. Resting spores increase from 7 percent below to 35 percent across the K-T boundary.
b) Dinoflagellates. Dinoflagellates in other places around the globe also were little affected by the K-T event (Bujak and Williams, 1979). Hultberg (1986) in Scandinavia records no accelerated rates of extinction across the K-T boundary . Danish dinoflagellates responded more by appearance of new species than by extinctions (Hansen, 1977), as did Seymour Island assemblages (Askin, 1988).
c) Yes other plankton did suffer massive extinctions but it wasn't because of the Asteroid or K-T event.
Marine calcareous microplankton, the coccolithophorids and planktonic foraminifera, were hit hardest of all by the K-T event. Thierstein (1981) proposes that the coccolithophorids extinctions were the most severe plankton extinction event in geologic history; via a "deconvolution" process, Thierstein (1981, 1982) reduced a Cretaceous-Tertiary "transition," in which Cretaceous assemblages were replaced by "new" Tertiary taxa, to an instantaneous catastrophe. Perch-Nielsen et al. (1982) note that the "catastrophic event"at the K-T boundary did not result in geologically instant extinction of the calcareous nannoplankton, and that most Cretaceous species survived the event. At DSDP Site 524, a sample above the K-T boundary contains 90 percent Cretaceous species. Isotopic analysis indicated that the Cretaceous species were not reworked specimens, but represented survivors of the K-T event that continued to reproduce in the earliest Tertiary oceans. The relict species became extinct some tens of thousands of years after K-T boundary time, probably via environmental stresses.
Finally, Microfossils were actually found in the Chicxulub crater itself!!! and even though they are essentially at "Ground Zero" they show no ill effects. So how could an Asteroid cause negative effects on life on the other side of the globe but not where it hit?
"Microfossils were actually found in the crater itself."
After a period of time wouldn't microfossils have drifted in from elsewhere and settled in the crater? All kinds of things are found in the crater. The question is how long after the crash did they get there?
Do you have any information on the Shiva Crater by India, which was a lot larger than Yucatan and about the same age. If it in fact is verified could it explain some of the timing anomolies regarding timing of extinctions of various organisms large and small?