New paper constraining the time span of the Yixian Formation and arguing for non-catastrophic causes for excellent preservation in its fossils

[ceratopsian]

It's paywalled sadly! Here's the link to the introduction and abstract in PNAS, lead author Scott MacLennan:

https://www.pnas.org/doi/10.1073/pnas.2322875121?et_rid=1068999283&et_cid=5420063

And if you prefer to read the abstract here:

"Abstract
Northeast China's Early Cretaceous Yixian Formation preserves spectacular fossils that have proved extraordinarily important in testing evolutionary hypotheses involving the origin of birds and the distribution of feathers among nonavian dinosaurs. These fossils occur either flattened with soft tissue preservation (including feathers and color) in laminated lacustrine strata or as three-dimensional (3D) skeletons in "life-like" postures in more massive deposits. The relationships of these deposits to each other, their absolute ages, and the origin of the extraordinary fossil preservation have been vigorously debated for nearly a half century, with the prevailing view being that preservation was linked to violent volcanic eruptions or lahars, similar to processes that preserved human remains at Pompeii. We present high-precision zircon U-Pb geochronology from cores and outcrops, demonstrating that Yixian Formation accumulation rates are more than an order of magnitude higher than usually estimated. Additionally, we provide zircon provenance and sedimentological data from 3D dinosaur fossils, which imply that their death and burial occurred in collapsed burrows, rather than via a catastrophic volcanogenic mechanism. In the studied area, the three principal fossil-rich intervals of the Yixian occur as a cyclic sequence that correspond to periods of high precipitation. Using Bayesian–Markov Chain Monte Carlo approaches, we constrain the total duration of the sequence to less than ~93,000 y and suggest that climatic precession paced the expression of these cyclic sediments. Rather than representing multiple, Pompeii-like catastrophes, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous continental community."

[Halichoeres]

I have access through work, so if anybody would like a copy, just message me your email address and I'll send you the pdf. Very interesting finding, I'm looking forward to reading through it myself when I have some time.

[Sim]

It's interesting.  I wonder if that means models of Mei sleeping outside are slightly inaccurate according to this paper?