The skull length of the basal eusauropod, Patagosaurus is about 60 centimetres (24 in).
One of the most basal eusauropods, Shunosaurus, has two characteristic features of the eusauropod elongated neck: the incorporation of the equivalent of the first dorsal vertebra into the cervical region of the spine, and the addition of two cervical vertebra in the middle of the cervical vertebrae.

Other synapomorphies of Eusauropoda includes a retracted position of the external nares.
Unlike prosauropods and theropods, which have a snout with smooth, unprotruding alveolar and subnarial regions, eusauropods have snouts with “stepped anterior margins”.
 Further distinguishing features of eusauropods include the absence of the contact between the squamosal and the quadratojugal, the absence of the anterior process of the prefrontal, and a distally elongated anterior ramus of the quadratojugal.
Separating the anteroventral process of the nasal from the posterolateral process of the premaxilla, eusauropods also have a long maxilla that forms the posteroventral margin of the external naris.
The skull length of the basal eusauropod, Patagosaurus is about 60 centimetres (24 in). One of the most basal eusauropods, Shunosaurus, has two characteristic features of the eusauropod elongated neck: the incorporation of the equivalent of the first dorsal vertebra into the cervical region of the spine, and the addition of two cervical vertebra in the middle of the cervical vertebrae.
Other synapomorphies of Eusauropoda includes a retracted position of the external nares. Unlike prosauropods and theropods, which have a snout with smooth, unprotruding alveolar and subnarial regions, eusauropods have snouts with “stepped anterior margins”.  Further distinguishing features of eusauropods include the absence of the contact between the squamosal and the quadratojugal, the absence of the anterior process of the prefrontal, and a distally elongated anterior ramus of the quadratojugal. Separating the anteroventral process of the nasal from the posterolateral process of the premaxilla, eusauropods also have a long maxilla that forms the posteroventral margin of the external naris.
Eusauropoda