In a 2013 Master's thesis (summarized in a published paper by different authors in 2019), paleontologist Carolyn Gale Levitt histologically studied the long bones of Kosmoceratops (femora of the adult holotype and the assigned subadult or adult UMNH VP 21339) and Utahceratops to examine indicators of growth and maturity in the bone microstructure (until then the only chasmosaurines ever sampled for this).
The bone tissue had a high number of osteocytes (bone cells) as well as a dense network of blood vessels, including radially oriented vascular canals (blood canals running towards the bone interior), indicating sustained rapid growth.
These features also indicate that ceratopsians had an elevated metabolism and were homeothermic endotherms (or "warm-blooded"), like modern birds and mammals.
The Kosmoceratops and Utahceratops bones sampled by Levitt did not show evidence of lines of arrested growth (annual growth lines), and compared with the ceratopsids Pachyrhinosaurus, Centrosaurus, and Einosaurus from further north which did have growth lines, this may indicate that bone growth reacted to climate and that Kosmoceratops and Utahceratops could sustain their growth throughout the year due to their more equitable southern climate.
The lack of growth lines also means that the individual ages of the Kosmoceratops and Utahceratops specimens cannot be estimated, but Levitt determined that the examined Kosmoceratops specimens were subadult to adult, ruling out Fowler and colleagues' 2011 claim that they represented immature Vagaceratops.
She also determined that the largest Kosmoceratops and Utahceratops were adults, and therefore ruled out that one was the juvenile of the other.

In a 2017 Master's thesis, paleontologist Nicole Marie Ridgwell described two coprolites (fossilized dung) from the Kaiparowits Formation which, due to their size, may have been produced by a member of one of three herbivorous dinosaur groups known from the formation: ceratopsians (including Kosmoceratops), hadrosaurs, or ankylosaurs (rarest of the three groups).
The coprolites contained fragments of angiosperm wood (which indicates a diet of woody browse); though there was previously little evidence of dinosaurs consuming angiosperms, these coprolites showed that dinosaurs adapted to feeding on them (they only became common in the Early Cretaceous, diversifying in the Late Cretaceous).
The coprolites also contained traces of mollusc shell, arthropod cuticle, and lizard bone that may have been ingested along with the plant material.
They were found near other herbivore coprolites that contained conifer wood.
Ridgwell pointed out that the dental anatomies of ceratopsians and hadrosaurs (with dental batteries comprising continuously replaced teeth) were adapted to process large quantities of fibrous plants.
The different diets represented by the coprolites may indicate niche partitioning among the herbivores of the Kaiparowits Formation ecosystem, or that there was seasonal variation in diet.
In a 2013 Master's thesis (summarized in a published paper by different authors in 2019), paleontologist Carolyn Gale Levitt histologically studied the long bones of Kosmoceratops (femora of the adult holotype and the assigned subadult or adult UMNH VP 21339) and Utahceratops to examine indicators of growth and maturity in the bone microstructure (until then the only chasmosaurines ever sampled for this). The bone tissue had a high number of osteocytes (bone cells) as well as a dense network of blood vessels, including radially oriented vascular canals (blood canals running towards the bone interior), indicating sustained rapid growth. These features also indicate that ceratopsians had an elevated metabolism and were homeothermic endotherms (or "warm-blooded"), like modern birds and mammals. The Kosmoceratops and Utahceratops bones sampled by Levitt did not show evidence of lines of arrested growth (annual growth lines), and compared with the ceratopsids Pachyrhinosaurus, Centrosaurus, and Einosaurus from further north which did have growth lines, this may indicate that bone growth reacted to climate and that Kosmoceratops and Utahceratops could sustain their growth throughout the year due to their more equitable southern climate. The lack of growth lines also means that the individual ages of the Kosmoceratops and Utahceratops specimens cannot be estimated, but Levitt determined that the examined Kosmoceratops specimens were subadult to adult, ruling out Fowler and colleagues' 2011 claim that they represented immature Vagaceratops. She also determined that the largest Kosmoceratops and Utahceratops were adults, and therefore ruled out that one was the juvenile of the other.
In a 2017 Master's thesis, paleontologist Nicole Marie Ridgwell described two coprolites (fossilized dung) from the Kaiparowits Formation which, due to their size, may have been produced by a member of one of three herbivorous dinosaur groups known from the formation: ceratopsians (including Kosmoceratops), hadrosaurs, or ankylosaurs (rarest of the three groups). The coprolites contained fragments of angiosperm wood (which indicates a diet of woody browse); though there was previously little evidence of dinosaurs consuming angiosperms, these coprolites showed that dinosaurs adapted to feeding on them (they only became common in the Early Cretaceous, diversifying in the Late Cretaceous). The coprolites also contained traces of mollusc shell, arthropod cuticle, and lizard bone that may have been ingested along with the plant material. They were found near other herbivore coprolites that contained conifer wood. Ridgwell pointed out that the dental anatomies of ceratopsians and hadrosaurs (with dental batteries comprising continuously replaced teeth) were adapted to process large quantities of fibrous plants. The different diets represented by the coprolites may indicate niche partitioning among the herbivores of the Kaiparowits Formation ecosystem, or that there was seasonal variation in diet.
Kosmoceratops