Diverse vertebrate assemblage of the Kilmaluag Formation (Bathonian, Middle Jurassic) of Skye, Scotland

Abstract

The Kilmaluag Formation on the Isle of Skye, Scotland, provides one of the richest Mesozoic vertebrate fossil assemblages in the UK, and is among the richest globally for Middle Jurassic tetrapods. Since its discovery in 1971, this assemblage has predominantly yielded small-bodied tetrapods, including salamanders, choristoderes, lepidosaurs, turtles, crocodylomorphs, pterosaurs, dinosaurs, non-mammalian cynodonts and mammals, alongside abundant fish and invertebrates. It is protected as a Site of Special Scientific Interest and by Nature Conservancy Order. Unlike contemporaneous localities from England, this assemblage yields associated partial skeletons, providing unprecedented new data. We present a comprehensive updated overview of the Kilmaluag Formation, including its geology and the fossil collections made to date, with evidence of several species occurrences presented here for the first time. We place the vertebrate faunal assemblage in an international context through comparisons with relevant contemporaneous localities from the UK, Europe, Africa, Asia and the US. This wealth of material reveals the Kilmaluag Formation as a vertebrate fossil assemblage of global significance, both in terms of understanding Middle Jurassic faunal composition and the completeness of specimens, with implications for the early evolutionary histories of mammals, squamates and amphibians.

The Making of Calibration Sausage Exemplified by Recalibrating the Transcriptomic Timetree of Jawed Vertebrates

“…The crucial difference may be that Lepidosauria did not have a maximum age, but this does not explain the very short internodes from Squamata to Iguania in my results. I should point out that the oldest likely squamate remains are close to 170 Ma old (reviewed in Panciroli et al, 2020 ).…”

“…Parviraptor ” by Haddoumi et al (2015) . Other material—vertebrae and jaw fragments from Europe and North America discussed in Panciroli et al (2020) —was originally assigned to “cf.” or “aff. Parviraptor ,” including but not limited to the late Bathonian or earliest Callovian Eophis , the Kimmeridgian Diablophis and Portugalophis , and Parviraptor itself from around the Jurassic/Cretaceous (Tithonian/Berriasian) boundary.…”

“…As mentioned, all these remains are very fragmentary, and all are disarticulated; according to a reviewer, new, apparently unpublished material shows the “parviraptorids” are not snakes, and indeed Panciroli et al (2020) were careful not to state in the text whether they agreed with the referral to the snake stem, designating “cf. Parviraptor sp.” as “Squamata indet.” in their faunal list ( Table 1 ).…”

The making of calibration sausage exemplified by recalibrating the transcriptomic timetree of jawed vertebrates

“…We’ll see if changing the minimum age of Toxicofera from 167 Ma to 130 Ma has spread them out again – though if so, most likely in the other direction, towards yet younger ages. I should point out that 169 Ma is the approximate age of the oldest likely squamate remains (reviewed in Panciroli et al, 2020).…”

First dinosaur from the Isle of Eigg (Valtos Sandstone Formation, Middle Jurassic), Scotland

“…The Bajocian-Bathonian Great Estuarine Group on Skye provides avivid picture of the diverse Middle Jurassic ecosystem of the Inner Hebrides. It comprises a series of lagoonal and deltaic sedimentary rocks (Andrews 1985) that have yielded a wealth of vertebrate material, including marine, terrestrial and flying archosaurs, turtles, squamates, lissamphibians, tritylodontids, and mammaliaforms (e.g., Evans et al 2006;Anquetin et al 2009;Anquetin 2010;Wills et al 2014;Young et al 2016a;Panciroli 2017aPanciroli , b, 2018Panciroli , 2019Panciroli , 2020Yi et al 2017).…”