Saturday, August 9, 2014

Prehistoric Warfare Episode 2: Dilophosaurus vs Sarahsaurus




Now for something different. In 2004, Animal Planet showed as new series called Animal Face Off, a series reconstructing conflicts between coexisting animals. While the execution was clumsy and lacking, the concept is strong and I think easily applied to prehistoric fauna.  Ideally, there would be professionals discussing the situations, but unfortunately, you have only me. First I will compare the animals, and then depict their behavior, before concluding with the final battle.  The outcome will be my personal opinion; and there would be many times when the outcome would be decidedly different. This is not a scientific consensus, but one researcher’s opinion.

We all love dinosaur battles. They’re always a high point in a film. It’s childish, but it’s just plain fun. So, I’m hoping to use this opportunity to use this almost-universal appeal to get people thinking and talking about ecology, biomechanics, and behavior. Only one or two of these stories will be based on actual fossils-the rest are likely possibilities that must have happened sometime or another. In real life, animals usually don’t fight on even terms, but it does happen. Sometimes prey turn the tables, sometimes predators quarrel between themselves, but it can happen. I hope you enjoy this. Again, first I will have two scenes, one for each animal showing them in their habitat and showcasing their particular skills, then finally concluding with a battle between the two.


I MUST WARN THAT  THIS WILL BE VIOLENT. IF YOU HAVE A PARTICULARLY VIVID IMAGINATION, OR HAVE AN AVERSION TO GRAPHIC NATURALISTIC VIOLENCE, I STRONGLY SUGGEST NOT CLICKING ON THE CUT




The last time on this feature, we saw a dinosaur predator come up as second-rate compared to its rauisuchid rival. A mass extinction, however, has changed everything. A mysterious catastrophe has caused a total ecological upheaval. The giant Plateosaurus is extinct, but new families of sauropodomorphs have arisen. Some are gracile bipeds, other are giant quadrupeds-the first sauropods. Dicynodonts are now extinct. Aetosaurs and Silesaurs, their successors, have also fallen to the extinction. Their predators; the rauisuchians and ornithosuchians are also gone. In this catastrophe, dinosaurs have taken over.

The time is the Sinemurian, about 192 million years ago. It’s dry-it will remain so for several more million years. The best analogy for this area is an oasis by a seaside desert, like the large oases of Western Tunisia. This will be the sandstones of northern Arizona in the present day, but the American coast is further inland and lakes dot the desert landscape. 

Araucaria trees form the open, scattered forests, with cycads filling in the gaps. It’s the beginning of the wet season, and animals are beginning to breed with the new greenery. Silesaurs have been replaced with small, lithe heterodontosaurs. A large armored dinosaur, the first of a new type, browses in the cycads. This is Scelidosaurus, ancestor to the great armored dinosaurs in the future. It’s a new species, and has not displaced its more nimble ancestors however.

In its wake are a pair of Scutellosaurus, who at first glance look more like the heterodontosaurs. They’re small, slender, and bipedal, unlike the big, bulky quadruped that breaks the cycad ferns as it trundles along. However, a close inspection will reveal bony armor.  They’re armored from the attacks of small dinosaurs and primitive crocodiles like the lithe Kayentasuchus and the more advanced, heavier Protosuchus that is replacing the former species.

Their teeth are simple, broad bladed leaf-cutters and they lack the beak of their larger, more advanced relative. They prefer the young shoots exposed by the Scelidosaurus’ munching and the crushed fern detritus. They’ve just come from the water hole on their usual game trail. For their routine-based brains, they use the same paths over and over again from hatchlings into old age.

This predictability, however, leads to routines in their predators. Usually it’s the smaller theropod Megapnosaurus, descended from Coelophysis and nearly identical. However, the Scutellosaurs adjust their behavior by trailing the giant Scelidosaurus, which can ably protect them with its armored flail of a tail.  However, today is different. Watching them, in the cover of a large cycad, is their predator for today. At 20 feet and almost 1,000 lbs, he is the largest predator of the Jurassic. He is a descendant of Liliensternus, but without the rauisuchians to keep him down, he’s as big as they are, but still light enough to run down most of the prey.  Last week he killed a Kayentasuchus, but this time he returns to his old game trail.


With yellow and black skin and a pair of bright red-orange crests, he’s pretty obvious. His best chance in stalking is to lurk in the groves to maximize his chances. Right now, he waits behind a tree for the prey to come into view. He first sees the Scelidosaurus. His mind associates it with bad memories. He’s fought them before-the odds are against him. For a brief second he backs away, but his attention span is seized by new, potential prey. 

Yes, Scutellosaurus. He’s had them before. They’re delicious. Caution and hunger engage in the endless debate inside the mind of any predator. Hunger makes him shadow the small group. Caution makes him wait until they’re out of range of the Scelidosaurus’ tail. Then hunger has the final say-he strikes.


He’s more than four feet at the hip-his long legs deliver powerful strides. Scelidosaurus’ brain activates its defense mode at the sudden movement. The tail swipes, and is only narrowly dodged. Ducking under the tail, Dilophosaurus ignores the larger herbivore and heads straight for the smaller prey. They flee into the cycads with Dilophosaurus at their tails.

He strikes, but his glancing blow and weak teeth fail to penetrate the armor. Instead, both animals are slowed as the other Scutellosaurus makes her getaway. The other isn’t as lucky; Dilophosaurus kicks down, knocking the slower dinosaur into the dust. It rolls to right itself, narrowly avoiding the snapping jaws. Another kick knocks the Scutellosaurus back down, and this time, Dilophosaurus grabs with his claws. They don’t piece the thick armor of the sides, but they provide enough leverage for Dilophosaurus to lift the prey off the ground and aim a slash. The first bite severs the femoral artery. The second one is more immediate, slashing open the neck  With a hard yank, the large curved teeth slice though the thinner skin of the throat, severing arteries and windpipe with a single, efficient movement.

Feeling the Scutellosaurus go limp in his hands, he drops it only to gingerly manipulate the body with his claws. His teeth cleanly slice through the flesh of the underside and limbs. He will leave the armor and larger bones to scavengers, but the rest he picks clean with his narrow, precise snout’s clean bites. It’s a snack for a large endothermic predator like Dilophosaurus, but it will sate his hunger; yesterday’s cynodont and lungfish are supplanted quite nicely. Tomorrow he will hunt again, and if he’s lucky will take a larger prey.






Another grove of trees at the lake will not be able to provide cover, however. It’s currently being stripped. At 10 feet tall, these Aracauria are out of the reach of the ornithiscians, but not tall enough to avoid the sauropodomorphs. About 5 or 6 Sarahsaurus browse together, using their broad clipping teeth to chop up the fibrous leaves and processing them in their pebble-filled gizzards. It’s the formation of a herd; their families and groups are informal, based on age groups. These 10 year olds have been together for only a month but they’ve already mated multiple times amongst each other.  It’s not their first time; by this state in their life reproduction’s part of their routine and they’re at their peak size of about 16 feet long.

Some have even started to lay nests and keep lazy but constant watch on them. Predators will not be tolerated around their nests, but they’re easily distracted. This is something a certain Megapnosaurus is counting on. He’s been frustrated by the competition; other predators, mostly his own species, have picked clean a nearby turtle carcass, depopulated the shallower cynodont burrows, and cleaned the riverbank of crabs and lungfish. Last week’s shark carcass brought just enough calories for today. This time, he’ll try his luck at egg-robbery.


He’s timed it right in terms of eggs-all the females have laid their eggs and no other thieves have touched them. Now all he has to do is duck in, eat as many as he can while their slow-witted guardians are distracted, and then make a getaway when they move. It’s a simple plan; he’s done it before, and he’s been lucky.
The plan is enacted; one of the sauropods browsing near the egg has finished her tree, and moves towards another. She plants her long claws into the bark and stands parallel to the trunk. With a powerful movement of her strong forelimbs, she pulls down the tree while pulling herself up at the same time. This allows her head to reach the top and start feeding.


Meanwhile, Megapnosaurus is tucking into the nest in front of him. Eggs are a rare treat-they can be well guarded, but they’re full of protein and fat. He’s too distracted to notice the wind shifting. He’s too distracted to notice a big female turn from her tree and look in his direction. He’s too distracted to react until she’s already on top of him.

He hears the low growl, turning to see his attacker. Too late to run, he tries to deter her with a snap of his razor-lined jaws. It’s not a direct hit, and it barely leaves a scratch on her neck. With a bellow of rage, she swipes at him. Sarahsaurus is armed with four to five-inch curved claws, the largest on her thumbs.  Sloths and anteaters in the Holocene are well-armed with similar claws, and can inflict serious damage on larger cats and humans that prey on them. The lightly built skull of Megapnosaurus barely withstands the impact of her powerful swipe, the claws slashing his face badly.

Stunned and blinded by his own blood, Megapnosaurus can’t react to further bloods. Another swipe rips open his neck, the claw opening an artery. A third strikes him solidly in the torso, knocking him sideways off his feet and sending him flying through the air. Already dying from his grievous wounds, his life ends suddenly when the strike caves in his ribs and mashes in his internal organs with a combination of impact and acceleration.  He’s dead before his body crashes to land, bounces with remaining momentum, and tumbles into the dust.


Sarahsaurus doesn’t make sure he’s dead. Her brain is simple and her anger passes after one last roar at the corpse. The eggs are safe, and the smell of living enemy is passed. The other Sarahsaurs only briefly paused to glance at the violence, and return to their trees with the mental equivalent of a shrug. They don’t care about the lost eggs or the fight. The predator’s gone and the eggs have already been laid. That’s all they know and need to know.





In nature today, predators usually don’t eat large, dangerous prey. However, they do take chances when they have to, especially when other prey is scarce. In this case, however, it’s a gamble of opportunism. The lush plants have attracted a multitude of herbivores ranging in size from heterodontosaurs to prosauropods. However, there is a downside as some areas become more overbrowsed than others. Dilophosaurus has eaten only small prey lately-a Protosuchus here, a heterodontosaur there, and the previous week’s Scutellosaurus have been as large as prey gets. As the rains go on, Dilophosaurus finds his stomach growling for meatier fare. Another day of rain lowers visibility, and by the time it’s over, many of the prey have moved on to fresh forage.

Big-game hunting has previously been a domain only for rauisuchids in the Triassic, but as the theropods have flourished and grown in size, they have begun to take larger and larger prey. Large predators have the advantage of being able to overpower more kinds of prey than smaller animals, but the cost of size is lots of calories. Dilophosaurus’ metabolism requires a lot of meat, requiring larger and larger prey. At this point in time, predators have become larger than their prey, and although the prey is well-armed, Dilophosaurus can eat almost anything. Or can it?

As the rain dies down and the sky clears up, Dilophosaurus flares its nostrils and pivots his head from side to side. The large crests limit Dilophosaurus’ forward vision, but the sauropodomorphs have evolved laterally placed eyes to cover large visual ranges as well. It all depends on which animal sees which first.

He’s lucky this time; he can smell prey nearby. His nose is sensitive enough to identify the species, and his brain recognizes body shapes and sizes and associates them with past experiences. Right now, Dilophosaurus smells large but unarmored prey. Instinctively, he moves to the nearest cover as his begins his approach.  His luck stays-he sees the Sarahsaur herd, but it unnoticed in turn. Perfect.

A small flock of heterodontosaurs see him, and scatter as he dislodges them from the brush. Fortunately, the prosauropods don’t notice. More alert dinosaurs will learn to react from sudden movement, activating more complex defensive behavior. Prosauropods react only in the short term. Unless they distinctly smell or see a predator, they won’t change their standard behavior.

As usual, they’re eating. Big animals require lots of food, as mentioned before, and for plant eaters it means spending most of the time eating. This is inefficient as plant fiber isn’t very nutritious, so herbivores compensate by bulk and ways to process it. In this case, it’s the first gizzard. As sauropodmorphs evolve, they will increase in size, partially to increase the size of their digestive tract and gizzard to more efficiently process the food.

Dilophosaurus draws closer, moving as quickly as possible to take advantage of the wind at his face.  A Kayentasuchus and Scelidosaur shuffle out of the way, but he pays them no mind. At the moment, the Sarahsaurs have split up, having finished one cycad and spreading out to others. The nearest one is the big female that slew the Megapnosaurus, a poor target but the one he’s singled out. Other Meganosaurs cannibalized the corpse, and Dilophosaurus wouldn’t care even if he had seen it.  All he sees is prey.

Meanwhile, the Sarahsaurus and her clan are in their usual habit, each picking a cycad to browse. The sharp leaves and horny trunk of the plants evolved to discourage browsers, but the herbivores simply push and slash the blades aside with clawed paws and reach up and over into the softer parts with their long necks.  It’s efficient, and an impetus for the plants to reproduce more and grow taller. In turn the herbivores will grow bigger and develop more efficient feeding physiology.

Dilophosaurus’ feeding, on the other hand, is less food processor and more teppanyaki chef, and less grocery and more murder.  He has to find a target and bring it down. While plants are harder to digest than meat, they don’t fight back or run away, so the nature of the predator is speed, surprise, and dangerous weapons.

Right now he has surprise, an element he must maintain. He doesn’t run yet-he takes quick but long steps towards the prey.  The wind, for the moment, is on his side. If all goes well, he can quickly bring down the Sarahsaurus before she can even notice he’s there. He’s done it before to juveniles and subadults. This could go very easy if his luck holds.

It’s when he is within striking distance that his luck turns, or rather, the wind. Suddenly Sarahsaurus can smell him. Alarms go off in her head, and she turns swiftly towards the source. Her vision isn’t that good, but she recognizes Dilophosaurus as a dangerous predator. She gives out a bellow and raises her claws in defense, alerting the rest of the group.

Dilophosaurus gambles-instead of withdrawing, he stands his ground and makes a mock charge. The jaws snap less than a foot away from her skin, and she instinctively swipes at him. Despite the large crests, Dilophosaurus’ skull is light like those of its ancestors and relations. While it’s fragile and easily damaged from strong shocks, it’s also very mobile and allows for swift, agile movements.  In this case, Dilophosaurus darts his head back from Sarahsaurus’ attack.

Sarahsaurus raises herself to full height, emphasizing her size and allowing her to deliver more effective strikes at the large predator. Her head is raised high, giving her a better view of her attacker and keeping her vulnerable neck away from the deadly jaws.  When Dilophosaurus aims a bite at her neck, she shifts her neck and body to the side while slashing at him as he closes.

He reaches high to attack her throat, but it exposes his own throat to attack and barely escapes her claws. He goes for her stomach, but she briefly leans back on her tail to deliver a kick. Her feet are as well-armed as her hands, and a direct hit could disembowel Dilophosaurus. He leans out of the way on his long legs, and bites at her thigh. She’s slower to respond, and while he’s again driven off, Sarahsaurus’ leg is now slashed by the theropod’s teeth. First blood goes to Dilophosaurus.

She stumbles from the pain, giving Dilophosaurus an opening to attack again. This time he goes for the kill, but it’s a premature decision. Ironically, the injury causes Sarahsaurus to stumble out of the way of Dilophosaurus’ path. She catches him this time, slashing his shoulder and side. Her long thumb claw pierces into his flesh, scarring his scapula and staggering him in turn.

He backsteps away from a second, fatal blow, hissing in pain and flashing his teeth to draw off a third strike. In turn, she rears up again and raises her arms spread outwards while letting out a hiss of her own. There’s a standoff;  if he moves to attack, she can catch him again and inflict a more grievous injury. If she moves forward to attack or disengages, she risks letting Dilophosaurus get an opening.  For a moment, they catch their breaths, blood pouring from their wounds as their hearts beat fast from their adrenaline.

Flanking is a natural enough tactic for Dilophosaurus, but he’s not as sophisticated as his descendants. As he swiftly moves to attack Sarahsaurus’ side, she leans forward as the wound causes another stumble. Again, it foils Dilophosaurus’ own plans; as she leans forward, her tail raises and switches from support to club. Like a man swinging his cane or crutch at an attacker, Sarahsaurus’ tail swings, hitting Dilophosaurus right in his injury.

Reeling backwards in pain, Dilophosaurus allows Sarahsaurus to right herself and turn to face him again. He could give up now; his injuries are savage but not so to cripple him or bleed out. He could retreat now, and ambush Sarahsaurus later as she recovers from her injury. He’s too hungry, though, to reconsider. His brain is still in attack mode. He’s not bright enough to pull back now. He’s in pain, but not discouraged.

This time Dilophosaurus tries a new attack. First crouching to avoid another slash, he springs forward, slashing with his own claws and kicking out with clawed feet. The injured arm lazily swings, his shoulder too badly torn to strike. However, his feet land the critical hits. One slashes her stomach, and the second lands a hit on the same injured leg. 

Sarahsaurus falls forwards on her side, splashing into the mud. There’s a new flash of pain from her leg, a muscle spasm, another flash from her stomach, and finally a blast of shock, compounded by falling on her injured thigh. Flailing blindly as she falls, a thumb claw slashes Dilophosaurus’ other shoulder and thigh. If she was still fresh, those would be crucial blows in themselves, but it’s too late.

As the herbivore struggles to right herself, Dilophosaurus goes in for the kill. This time, he strikes true. The bite rips open her neck, but it doesn’t stop. It’s not a hard bone crushing bite like those of a tyrannosaur, or a rending bite of a rauisuchian, but a series of short, sharp snaps. His neck and jaws twitch as soon as they make contact, sawing his teeth into Sarahsaurus’ flesh. Each twitch sends the jaw rapidly slicing through the flesh like a teppanyaki chef chopping meat. His ginsu set of teeth, especially long in the upper jaw, are slender but still sharp, and they shred the muscles, sever the windpipe and arteries, and end Sarahsaurus’ life in shock and red mist.



It’s a well-earned victory, and he quickly takes advantage of it. He’s never killed an animal this big, and he will gorge himself until it’s physically impossible to eat more. As soon as his jaws finish ripping through the flesh of Sarahusaur’s neck, he moves on. A nip of the hooked tip of his snout opens the wound on her stomach, and he uses his narrow skull to snake into her abdomen to get at the nutritious organs underneath. He pulls out her liver first, devours it in a violent shredding motion of his jaws, then moves on to the other organs.
The kill will attract scavengers, but even though he’s wounded, he’s not afraid. It’s a bit of a distance for other Dilophosaurs to cross to get to his oasis, and hopefully his crest will advertise his identity to ward off other males and attract females. In fact, this fresh meal might be his ticket to a mate. He’s done this before. If the food lasts long enough, they can form a bonded pair and hunt together for a brief time until the next dry season.

Dilophosaurus’ win was lucky, but luck built on evolutionary success. The success of the theropod’s physical characteristics gave him agility, intelligence, and very effective armament. The rauisuchids’ extinction allowed him to grow even larger than they and their prosauropod prey.  Indeed, his African counterpart Dracovenator is putting pressure of Sarahsaurus’ sister species Massonspondylus and promoting the growth of new, bigger sauropods. 

Dilophosaurus may have won the day today and in this age, but the arms race will continue. Right now the size race favors the predators, but the tables will turn, and escalate, and force new forms of theropod to replace Dilophosaurus in order to prey on the grandchildren of Sarahsaurus. Their physiologies will become obsolete in a few million years, but they are the standard and the blueprint of things to come. Dilophosaurus will be overshadowed by the members of the dynasty, but for now, it is the king.




10 comments:

  1. Enjoyed your Dilophosaurus story. Reminds me of the tales in Walking With Dinosaurs BBC. I recently saw a full-sized model of Dilophosaurus at a CT museum, Dinosaur State Park (Rocky Hill CT). I never realized how big Dilophosaurus was until I visited the place.

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  2. Very cool, like a Walking with Dinosaurs script. A bit brave with the tail propping prosauropod. Is the third from the last pic with the dino figs one of your own?

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    Replies
    1. No, it is photography from another dinosaur collector-I don't own the Safari Dilphosaurus as of yet :)

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