BRACHAUCHENIUS LUCASI
The Last Pliosaur
Scientific Profile
🦈 Classification: Short-necked pliosaur (Pliosauridae)
⏳ Time Range: Late Cretaceous (100-90 mya)
🌎 Fossil Sites: Kansas, Texas, Utah (Western Interior Seaway)
Anatomy & Size
📏 Length: 5.2m (17ft) – size of a great white shark
🦴 Key Features:
-
Stocky torso with barrel-shaped body
-
1m (3.3ft) tail with small fluke
-
2m skull with conical teeth (ambush predator)
🏊 Locomotion: -
Four paddle-like flippers (front pair larger)
-
Estimated speed: 18-25 kph (11-15 mph)
Paleoenvironment
🌊 Habitat: Shallow tropical seas (~50m depth)
🐟 Prey: Fish, ammonites, smaller marine reptiles
🗺️ Notable Site: Delphos, Kansas (Niobrara Formation)
Evolutionary Context
🦕 Last of Its Kind: One of the final pliosaurs before their extinction (90 mya)
🔍 Convergent Evolution:
-
Resembled polycotylid plesiosaurs (e.g., Dolichorhynchops)
-
Despite not being closely related (see comparison below)
| Feature | Brachauchenius (Pliosaur) | Dolichorhynchops (Polycotylid) |
|---|---|---|
| Neck Length | Short (1/5 body length) | Moderate (1/3 body length) |
| Skull Shape | Massive, robust | Narrow, elongated |
| Flipper Size | Front > Rear | Nearly equal |
Fossil Record
🪨 Notable Specimens:
-
Kansas holotype (1903 discovery)
-
Fragmentary remains across American West
Why It Matters
🔬 Research Significance:
-
Shows pliosaur diversity persisted into Late Cretaceous
-
Demonstrates convergent evolution in marine reptiles
🎨 Visual Reconstruction Tips:
-
Color: Counter-shaded (dark back/light belly)
-
Posture: Front flippers angled downward for maneuverability
-
Environment: Add cretaceous fish (Xiphactinus) as prey
Rating: 8.5/10 (Would benefit from skeletal diagram)