Open Paleo

Macrurosaurus

Seeley, 1876 ma-KROOR-o-SAWR-us

From Greek makros (large) and oura (tail); meaning "large-tailed lizard"

113.2–100.5 million years ago Albian, Early Cretaceous
Early Cretaceous stages

Macrurosaurus is the name given to a genus of dinosaur from the Early Cretaceous. It was a titanosauriform which lived in what is now England. The type species, M. semnus, was named in 1876. A second species, M. platypus, may also exist.

Diagnosis

  1. Procoelous caudal vertebrae uniquely combined with absence of chevron bones in large animal
  2. Vertebral articulation transitions from procoelous anteriorly to biconcave posteriorly
  3. Neural arch supported on pedicles rising from centrum, depressed with no neural spine
  4. Centrum becomes elongated and rounded in dice-box form, converging toward crocodilian pattern
  5. Basal keel well-rounded with median ridge on ventral surface of centrum

Species

Macrurosaurus semnus Seeley, 1876

Type species

From Ancient Greek 'semnos' meaning 'stately' or 'impressive', an allusion to the imposing size inferred from the large caudal vertebrae.

Lectotype
CAMSM B55630 , Sedgwick Museum, University of Cambridge
Material
The first procoelous caudal vertebra of the Coldham Common series.
Notes
Seeley (1876) founded the species on two series of caudal vertebrae, about 25 from Coldham Common and 15 from Barton. Le Loeuff (1993) designated the first procoelous caudal of the Coldham Common series as the lectotype.
Horizon
Cambridge Greensand Member, West Melbury Marly Chalk Formation, Albian, Early Cretaceous , 113.2–100.5 million years ago The age of the older beds the specimen was reworked from.
Locality
Coldham Common, Barnwell, Cambridgeshire, United Kingdom Barrett and colleagues (2020) record that the Cambridge Greensand's tetrapods are "largely reworked from the underlying Gault Formation (upper Albian)", so the type takes the Albian of the Gault while the member it was found in is Cenomanian.

References

  1. Le Loeuff, J. (1993). European titanosaurids. Revue de Paléobiologie, Volume Spéciale 7: 105-117.

    Designates CAMSM B55630, the first procoelous caudal of the Coldham Common series, as the lectotype.

    leloeuff1993a
  2. Seeley, H. G. (1876). On Macrurosaurus semnus (Seeley), a long tailed animal with procoelous vertebrae from the Cambridge Upper Greensand, preserved in the Woodwardian Museum of the University of Cambridge. Quarterly Journal of the Geological Society of London 32: 440-444. doi:10.1144/GSL.JGS.1876.032.01-04.50

    Founds the species on two series of caudal vertebrae from phosphate workings in the Cambridge Upper Greensand, at Coldham Common, Barnwell, and at Barton.

    seeley1876a
  3. Hopson, P. M. (2005). A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report RR/05/01. British Geological Survey.

    Places the Cambridge Greensand Member at the base of the West Melbury Marly Chalk Formation.

    hopson2005a
  4. Barrett, P. M.; Bonsor, J. A. (2020). A revision of the non-avian dinosaurs 'Eucercosaurus tanyspondylus' and 'Syngonosaurus macrocercus' from the Cambridge Greensand, UK. Cretaceous Research 118: 104638. Elsevier BV. doi:10.1016/j.cretres.2020.104638

    Records that the Cambridge Greensand fauna is largely reworked from the Gault.

    barrett2020a