Mapusaurus vs Austroraptor
The summer has been hot this year, and the local waterways have slowly dried up and shrunk until only the biggest arteries in the area remain flowing. Even the largest local river is down to a fraction of its usual flow rate. There is some geological activity to the south, and local climate and hydrology are changing in what would later become Patagonia in modern day Argentina (Eberth et al. 2000). Local wildlife now must come to the shrinking river to get enough moisture to survive, and herds of sauropods regularly visit the water to drink.
Crouched in the shadows of some boulders near the bank, Austroraptor keeps an eye on activity near the river. She has been doing very well during this dry spell, catching fish much more easily in the reduced flow, using her excellent vision and long snout with strong conical teeth to snatch them out of the water (Novas et al. 2008). As an unusually long-legged dromaeosaurid theropod, Austroraptor is also one of the largest known raptors, and can cover long distances to run down many different prey animals.
As the sauropod herd settles in to drink, they are not alone. A young Mapusaurus has been trailing the group, hoping to pick off a smaller or weaker animal. She is not yet full grown, only nine meters long of the total twelve meters she will likely reach, and has recently left her family group to head out on her own (Coria and Currie, 2006). She has been harassing the herd for days, stressing the adults and lunging at stragglers. So far, she has not managed to land a meal, but each time she attacks, the reaction of her prey becomes a little slower. They are weakening as food and water are becoming scarce, and Mapusaurus is paying very close attention now. She is keyed up on high alert, soon she will catch her meal.
Her keen sense of smell evaluates the herd for any sign of sickness, and also takes note of another scent. It is Austroraptor, hiding near the water upwind. Mapusaurus immediately strides towards the source of the smell, wanting to investigate any other predator in the area, either as a rival to be wary of, or as something smaller to chase away.
Austroraptor sees Mapusaurus coming, and hesitates briefly. The large theropod heading her way is not THAT large, only a little bigger than herself. She steps out of the shadows and stands tall on her long legs, fluffing her feathers and displaying her claws, looking as big as she can. She would rather try intimidating this other predator first, rather than abandon her easy meal ticket right away.
Even though she is still an adolescent, Mapusaurus is full of the confidence inherited as the largest apex predator in the ecosystem. She switches from walking to sprinting within a few strides, and charges Austroraptor head on. She is in no mood to tolerate anyone taking away her chance at her hard earned meal of sauropod. Bluffing and display are no match for direct aggression, and Austroraptor scrambles to get out of the way.
Mapusaurus shoves and snaps at Austroraptor with her large wedge-shaped head. Being smaller and more agile, Austroraptor twists and turns, ducking out of reach, lashing out with the claws on her hands. She lands a few slashes on the neck and shoulders of Mapusaurus, and manages to avoid a deadly bite from the large serrated teeth. Austroraptor takes advantage of the cloud of dust kicked up by their scuffle and sprints all out, now running away for her life as fast as she can. Mapusaurus is no match for her speed, and only follows for a few strides before turning back to the river. Dust settles into the cuts on her neck and stings, but she ignores it as she heads back to her vigil on the sauropod herd.
EBERTH D. A., CURRIE P. J., CORIA R. A., GARRIDO A. C. & ZONNEVELD J.-P. 2000. Large-theropod bonebed, Neuquén, Argentina: Paleoecological importance. Journal of Vertebrate Paleontology 20: 39A.