Decades of fieldwork above the Cretaceous-Paleogene boundary in the Western Interior has produced dozens of articulated skeletons and/or skulls of champsosaurs, crocodilians, lizards, turtles, and mammals firmly in place in Paleocene sediments.To date, no dinosaur skulls, skeletons, or nests—fossils unlikely to survive reworking unrecognized—are recorded in museum collections across North America from these or contemporaneous formations ( ucmpdb.berkeley.edu; muse.museum.montana.edu/paleodb_pub/; si.edu/search/paleo/).Fassett et al.’s failure to present geochemical data that provide insight into the process and duration of recrystallization undermines their conclusion that their age estimates are closely associated with time of death and early fossilization of the dinosaurs in question.Without greater knowledge of the recrystallization process and its duration, it is difficult to interpret what useful information, if any, can be derived from U-Pb or Lu-Hf dating efforts on fossil bone. present the first use of laser ablation–multicollector–inductively coupled plasma–mass spectrometry (LA-MC-ICP-MS) U-Pb dating of fossil bone, but their reference to U-Pb dating studies of igneous zircon and titanite as being similar to the methods for recrystallized apatite is unsupported. (2011) present the detailed methodology required to ensure valid LA-MC-ICP-MS U-Pb geochronology of apatite.Last week, I was conversing with a female friend of mine at the bus stop. I begin reading, when suddenly I get a tap on the back. One of the girls points at my book and says “What are you reading there? ” After she’s done talking, I grab the book out of her hands and say “Yeah that was one of his inspirations. I’m going to read now.” I open up a page, and begin reading. I sighed, and realized that no matter what I did, they wouldn’t stop annoying me unless I confronted them. “Yeah, you come off as a disrespectful asshole.” I stretch out my arms and look left and right.The lineup was large, and few people were engaging in conversation. ” I tell her “It’s The Prince, by Niccolo Machiavelli. Not even one sentence in, and these chicks are already busting my balls. I realize everyone in the bus is quiet, and are all eyeing in on the conversation.How closely such a minimum age coincides with the pre-mortem age of the animal or with the depositional age of entombing sediments depends on many taphonomic variables, sediment geochemistry, groundwater flux history, and the porosity of fossil bone.Both samples analyzed (22799-D and BB1) are fossil bone fragments rather than articulated fossil skeletons and are therefore suspect of being reworked.
Our responses to specific comments by Renne and Goodwin (2012) are as follows: Fassett et al.Based on U-Pb dating of two dinosaur bones from the San Juan Basin of New Mexico (United States), Fassett et al.