Microlestes Quarry, Frome (Triassic of the United Kingdom)

Also known as Holwell

Where: England, United Kingdom (51.2° N, 2.4° W: paleocoordinates 35.7° N, 1.1° E)

• coordinate stated in text

• outcrop-level geographic resolution

When: Rhaetian (208.5 - 201.3 Ma)

• Rhaetian fissure infill, "Lower Rhaetic"

• bed-level stratigraphic resolution

Environment/lithology: fissure fill; lithified, green claystone and poorly lithified sandstone

• "The filling may be a peculiar greenish clay, or hard clay with pebbles, etc., or friable sand."

Size classes: mesofossils, microfossils

Collected by C. Moore, W. Kühne in 1860, 1939

Collection methods: bulk, peel or thin section, sieve,

• Moore collection at Bath Geology Museum.

Primary reference: R. Owen. 1871. Monograph of the fossil Mammalia of the Mesozoic formations. 24(110):vi-115 [R. Butler/R. Butler/M. Carrano]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 120898: authorized by Matthew Clapham, entered by Matthew Clapham on 23.11.2011, edited by Roger Benson, Richard Butler, Priscilla Vazquez, Matthew Carrano, Emma Dunne and Philip Mannion

Creative Commons license: CC BY (attribution)

Taxonomic list

 Lamniformes - Cetorhinidae
Pseudocetorhinus pickfordi n. gen. n. sp.4 Duffin 1998 basking shark
CD23, 1997/1-11
 Hybodontiformes -
Lissodus sp.9, "Acrodus minimus" = Lissodus minimus6
Lissodus sp.9 Brough 1935 elasmobranch
"Acrodus minimus" = Lissodus minimus6 Agassiz 1839 elasmobranch
 Hybodontiformes - Polyacrodontidae
"Hybodus cloacinus" = Polyacrodus cloacinus6
"Hybodus cloacinus" = Polyacrodus cloacinus6 Quenstedt 1858 elasmobranch
 Hybodontiformes - Acrodontidae
Palaeobates reticulatus n. sp.5 Duffin 1998 elasmobranch
CD18, M176
 Hybodontiformes - Pseudodalatiidae
Pseudodalatias sp.9 Reif 1978 elasmobranch
 Euselachii -
"Vallisia coppi" = Vallisodus coppi2, "Polyacrodus holwellensis n. sp." = Duffinselache holwellensis5
"Vallisia coppi" = Vallisodus coppi2 Duffin 1982 elasmobranch
"Polyacrodus holwellensis n. sp." = Duffinselache holwellensis5 Duffin 1998 elasmobranch
CD16, M181
 Synechodontiformes - Palaeospinacidae
Nemacanthus sp.9, "Palaeospinax rhaeticus" = Synechodus rhaeticus1
Nemacanthus sp.9 Agassiz 1836 elasmobranch
"Palaeospinax rhaeticus" = Synechodus rhaeticus1 Duffin 1982 elasmobranch
CD19-20, M181a-c
 Synechodontiformes -
"Hybodus minor" = Rhomphaiodon minor6
"Hybodus minor" = Rhomphaiodon minor6 Agassiz 1837 elasmobranch
 Chimaeriformes - Myriacanthidae
Agkistracanthus mitgelensis3 Duffin and Furrer 1981 chimaera
M186, a-e
 Palaeonisciformes - Birgeriidae
Birgeria sp.6, "Saurichthys acuminatus" = Birgeria acuminata6
Birgeria sp.6 Stensiö 1919 ray-finned fish
"Saurichthys acuminatus" = Birgeria acuminata6 Agassiz 1843 ray-finned fish
 Palaeonisciformes - Palaeoniscidae
"Gyrolepis alberti" = Gyrolepis albertii6
"Gyrolepis alberti" = Gyrolepis albertii6 Agassiz 1834 ray-finned fish
 Perleidiformes - Colobodontidae
Colobodus sp.6 Agassiz 1843
 Semionotiformes - Semionotidae
Sargodon tomicus6 Plieninger 1847
 Parareptilia - Procolophonidae
Procolophonidae indet.11 Lydekker 1889 parareptile
 Placodontia -
 Rhynchocephalia -
Gephyrosaurus sp.11 Evans 1980 rhynchocephalian
Gephyrosaurus evansae n. sp.10 Whiteside and Duffin 2017 rhynchocephalian
Holotype: Specimen BATGM CD1: anterior and mid region of the lower part of a right maxilla displaying emplacements for 24 pleurodont teeth
 Choristodera -
Pachystropheus sp.9 von Huene 1935 choristodere
 Diapsida - Trilophosauridae
Variodens sp.11 Robinson 1957 archosauromorph
Variodens inopinatus10 Robinson 1957 archosauromorph
Referred material: Specimen BATGM CD4, an anterior mid-region fragment of a left dentary
 Phytosauria -
Palaeosaurus sp.6 Riley and Stutchbury 1836 archosaur
 Saurischia -
Thecodontosaurus sp.6 Riley and Stutchbury 1836 sauropodomorph
 Morganucodonta - Morganucodontidae
"Eozostrodon parvus n. gen. n. sp." = Eozostrodon parvus7, "Eozostrodon problematicus n. sp." = Eozostrodon parvus7
"Eozostrodon parvus n. gen. n. sp." = Eozostrodon parvus7 Parrington 1941 mammaliaform
Holwell IX
"Eozostrodon problematicus n. sp." = Eozostrodon parvus7 Parrington 1941 mammaliaform
Holwell XIII
 Therapsida - Haramiyidae
"Microlestes moorei n. sp." = Thomasia moorei, "Microcleptes sp." = Thomasia8, "Microcleptes fissurae n. sp." = Thomasia antiqua8, "Thomasia anglica n. sp." = Thomasia antiqua8
"Microlestes moorei n. sp." = Thomasia moorei Owen 1871 mammaliaform
Bath Museum M211-M217, M222; YPM 13622A (molars)
"Microcleptes sp." = Thomasia8 Poche 1908 mammaliaform
Bath Museum M218 (a canine/incisor), M220 (four canines/incisors)
"Microcleptes fissurae n. sp." = Thomasia antiqua8 Plieninger 1847 mammaliaform
BMNH M2401A-C (molars)
"Thomasia anglica n. sp." = Thomasia antiqua8 Plieninger 1847 mammaliaform
Bath Museum M219, M221; YPM 13622b (molars)
 Dipnoi - Ceratodontidae
Ceratodus sp.9 Agassiz 1838 lungfish
Penegephyrosaurus curtiscoppi
Penegephyrosaurus curtiscoppi n. sp.10 Whiteside and Duffin 2017
Holotype: BATGM C193: a part of a left dentary with emplacements for five teeth