Triceratops

Triceratops was impressively large, around 9 m long and 2.5 m tall, and reaching a weight of around 5 - 8 tonnes (5,000 - 8,000 kg). It had a large, striking head, with a large boney frill and 3 horns - 2 large brow horns above the eyes (each reaching up to about 1 m in length), and one smaller nose horn above the nostrils. The largest known Triceratops skull is approximately 2.5 m long!

The body was robust, supported by four sturdy legs—shorter forelimbs with three hooves each, and longer hindlimbs with four. Fossilized skin impressions show that it had large, pebbly scales, some up to 10 cm in size.

There has been some debate about Triceratops' posture. Early reconstructions suggested a sprawling forelimb posture to support the heavy skull. However, more recent studies based on fossil trackways and improved skeletal reconstructions indicate that Triceratops likely held its forelimbs in a semi-upright position. This shows that its anatomy was well-adapted to bear the head’s weight without needing a sprawling stance.

Triceratops had a sharp, curved beak ideal for plucking low-growing vegetation, including palms, cycads, and ferns. Its teeth were arranged in dental batteries: around 36–40 vertical columns per battery, each with 3–5 teeth stacked vertically. With one battery on each side of both jaws (four in total), Triceratops could have up to 800 teeth, though only a fraction were in use at any given time. The lower teeth constantly grew and erupted to push out and replace the worn teeth on top. These teeth were used to grind plant matter and help them extract as much energy as possible from these tough fibrous plants.

Several theories have been suggested for the exact function(s) of the horns and frills in Triceratops and other ceratopsian dinosaurs. While popular media often show these being used mostly for combat and defense, research paints a more complex picture. The prevailing theory now is that the frills played a role in socio-sexual signaling. The shapes & sizes of frills across ceratopsian dinosaurs were spectacularly diverse, suggesting these structures were used to display strength, dominance, and reproductive fitness - much like the colorful displays observed in many modern animals. Notably, the robust, solid frill of Triceratops is an exception rather than the norm among ceratopsians. Additionally, the fact that juveniles exhibit much less developed horns and frills than adults suggests that these features evolved primarily for socio-sexual display, rather than for species recognition or defense.

There is some evidence of horns being used in combat – healed bite marks on a Triceratops horn from its mortal enemy, Tyrannosaurus Rex, show that it did use its horns to fend off an attack. Additionally, some skull damage has led to the hypothesis that these horns might have been employed in intraspecies combat (fighting with other Triceratops), perhaps in contests over mates, although this idea remains debated.