Original: According to weight estimates by Ryosuke Motani a Stenopterygius weighed around 163 - whilst a Ophthalmosaurus icenicus weighed 930 -.
Simplified: According to weight estimates by Ryosuke Motani, a Stenopterygius weighed around 163 - whilst a Ophthalmosaurus icenicus weighed 930 â "950kg (1.03 â" 1.04 short tons).