Tuesday, September 8, 2020

[Paleontology • 2020] Vectaerovenator inopinatus • A highly Pneumatic middle Cretaceous (Lower Greensand) Theropod from Isle of White, UK

 

 Vectaerovenator inopinatus
Barker, Naish, Clarkin, Farrell, Hullmann, Lockyer, Schneider, Ward & Gostling, 2020


Abstract
A series of axial elements from the Aptian Ferruginous Sands Formation of the Lower Greensand Group, discovered on the foreshore near Knock Cliff on the Isle of Wight, UK are (bar some isolated teeth and fragmentary postcranial material from the Cenomanian Cambridge Greensand) the youngest non‐avian theropod remains reported from the British Mesozoic. These specimens have the potential to shed light on a poorly known section of the European dinosaur record. Consistency in size, appearance and adhering matrix indicates that the vertebrae belong to the same individual. This was a mid‐sized tetanuran, the presence of several diagnostic characters indicating that it should be recognized as a new taxon, herein named Vectaerovenator inopinatus. The cervical and dorsal vertebrae are camerate and highly pneumatic. Tetanuran features include opisthocoelous cervicals and pneumatic foramina located within fossae; however, assigning this specimen to a specific clade is problematic. Within Tetanurae, Vectaerovenator possesses axial structures and homoplastic features seen in megalosauroids, carcharodontosaurians and certain coelurosaurs. Not only is Vectaerovenator one of the UK's youngest non‐bird dinosaurs, and one of few valid British Greensand taxa, it is also the first diagnosable theropod taxon to be named from Aptian deposits of Europe.

Keywords: Aptian, Cretaceous, pneumaticity, theropod, vertebra


Figure 1: Locality map of the new theropod taxon and stratigraphy of the Ferruginous Sands formation at Knock Cliff, Isle of Wight (UK). A, map of the Isle of Wight (inset) and photograph of Knock Cliff at Shanklin (credit: Trudie Wilson), where the specimens were collected. B, stratigraphy of Knock Cliff, focusing on the Ferruginous Sands Formation; black triangle indicates Horse Ledge; white triangle indicates the location of the ‘pebble bed’. Based on Ruffell et al. (2002), Young et al. (2014) and Gale (2019). Scale bar represents 10 km. 


Figure 2: Silhouette of Vectaerovenator inopinatus showing the approximate position of the vertebral elements (see description for further discussion). Elements not to scale.

Systematic palaeontology
DINOSAURIA Owen, 1842 
THEROPODA Marsh, 1881 
TETANURAE Gauthier, 1986 
INCERTAE SEDIS 

Genus VECTAEROVENATOR nov.
 
Derivation of name: Vectis (Latin): referring to the discovery of this new taxon on the Isle of Wight; aero (Greek): ‘air’, referring to its high degree of skeletal pneumaticity; ‐venator (Latin): meaning hunter. We imagine the name to be pronounced ‘vect‐air‐oh‐ven‐ah‐tor’.
 

Vectaerovenator inopinatus sp. nov.  

Derivation of name: inopinatus (Latin): ‘unexpected’, referring to its surprise discovery in the notably dinosaur‐poor Lower Greensand strata of the Isle of Wight. The name thus translates as ‘unexpected Isle of Wight air‐filled hunter’.

Holotype: IWCMS 2020.407, 2019.84, 2020.400.

Diagnosis: Tetanuran theropod diagnosed by: conspicuous lateral furrow between the lateral margin of the postzygapophysis and prezygoepipophyseal lamina in cervical vertebrae; convex spinoprezygapophyseal laminae in anterior cervical vertebra; curved lamina bisecting the postzygocentrodiapophyseal fossa; external extension of the air sac ventral to the parapophysis of anterior dorsal vertebra; complex partitioning of the anteriormost dorsal pneumatic foramen into several internal pneumatic features; anterior articular facet of anterior dorsal vertebrae wider than centrum such that vertebra is T‐shaped in dorsal or ventral view; shallow fossae lateral to the base of the postzygapophyses in mid caudal vertebrae.

Type locality and horizon: Knock Cliff, Isle of White, UK. Upper Aptian, Lower Greensand, Ferruginous Sands Formation, Member XIII, Parahoplites nutfieldensis Zone (possibly Tropaeum subarcticum subzone; Fig. 1A).


Chris T. Barker, Darren Naish, Claire E. Clarkin, Paul Farrell, Gabriel Hullmann, James Lockyer, Philipp Schneider, Robin K. C. Ward and Neil J. Gostling. 2020. A highly Pneumatic middle Cretaceous Theropod from the British Lower Greensand. Papers in Palaeontology. DOI: 10.1002/spp2.1338