[D] Astrodon johnstoni [T]
Cretaceous Early Hauterivian Barremian
Saurischia Sauropodomorpha Sauropoda Titanosauria Incertae Sedis
Arundel Formation, Muirkirk, Maryland, US
Astrodon (Johnston, 1859) (= Astrodonius, Kuhn, 1961 / Astrodontaurus Johnston, 1858 vide Kranz, 2004) > Astrodon johnstoni (Leidy, 1865) > Astrodon nanus (Gilmore, 1921) >> Pleurocoelus nanus (Marsh, 1888) Astrodon johnstoni (Leidy, 1865) > Astrodon altus (Gilmore, 1921) >> Pleurocoelus altus (Marsh, 1888)
O.C. Marsh in 1888 proposed the name Pleurocoelus -Astrodon, for a very small sauropod from the same area measuring under 5 meters in length., which he believed to be the smallest known adult sauropod. He based his conclusions on presumably juvenile material excavated from nearby Swampoodle. However, in 1991, large teeth and an Astrodon femur (estimated at an original length near 2 meters) were discovered at a site adjoining and contiguous with Latchford\\\'s property. This confirms Astrodon as a large sauropod measuring at least 25 meters in the adult form.
Carpenter & Tidwell (2005) Reassessment of the Early Cretaceous Sauropod Astrodon johnstoni, Leidy 1865 (Titanosauriformes) in: Thunder Lizards eds. V. Tidwell & K. Carpenter Indiana University Press pp. 78-114
Abstract: Sauropod material from the Arundel Formation (Aptian-Albian boundary) of Maryland has been variously referred to Astrodon johnstoni Leidy 1865 or to Pleurocoelus nanus Marsh 1888. Most of the specimens are juvenile as demonstrated by the small size of the bones, the lack of neurocentral fusion, absence of an olecranon, and underdevelopment of muscle scars. Contrary to some recent statements, the Aurundel sauropod is diagnostic. Only a single sauropod taxon is present in the Arundel Formation, to which the name Astrodon johnstoni must be used under the Principle of the First Reviser of the International Code of Zoological Nomenclature.