Modern protoceratopsians all evolved from the Protoceratops-like herbivores that had already experienced a modest success in the later part of the Cretaceous.  These creatures probably evolved in Asia (and were certainly at their most populous in this place), but successfully invaded North America with forms such as Leptoceratops during the Cretaceous.

    As the Mesozoic became the Tertiary, ceratopsians worldwide went through an abrupt decline.  Even as Early as the middle Cretaceous, fossils indicate that the very largest ceratopsians (Clade Ceratopsidae) were beginning to dwindle in number, leaving only a few species like Triceratops horridus by the end of the Mesozoic. Ceratopsids continued to live in North America throughout the early Cenozoic, even evolving a number of giant forms paralleling modern hmungos, but even these remnants were snuffed with the passing of the Eocene.  No ceratopsids are alive today.

    While their larger cousins faded out, however, it seems the protoceratopsians of Eurasia fared much better.  Fragmentary remains indicate that during the Paleocene and Eocene, the protoceratopsids were already branching into a number of new forms, including some species of truly impressive size.  Many of these forms are strikingly similar to the extinct ceratopsids of North America, but the protoceratopsians, with their primitive teeth, their lack of brow horns (although many species possess flattened crests and nasal horns), and their cranial anatomies place all of these creatures with animals like Protoceratops.  Clade Protoceratopsia ties all of Spec's extant ceratopsians together.

    Protoceratopsia reached its apex during the Oligocene, when the all of this clade's major modern divisions first appear.  Fossils from this time indicate that, at their heyday, the protoceratopsids extend as far east as Japan and as far west as France, with sizable populations in India and Africa.  During the subsequent epochs, however, the protoceratopsids steadily lost ground to more fleet-footed ornithpods.  Today, only a few widely separated species represent the once-mighty ceratopsian family in the Old World.

PLATEOCEROSIDAE
    The plateocerosids (along with the enigmoceratopsids) form the clade Protoceratopsoidea, the modern forms most similar to their ancient protoceratopsid precursors.  A Home-Earth paleontologist would not be at all surprised to find  plateocerosid material in a Cretaceous fossil bed; the clade has accumulated almost no change over the last 65 million years.

SAMPLE TAXA:

• Sunhorn

ENIGMOCERATOPSIDAE

    Enigmoceratopsids evolved in southern Eurasia during the Eocene as very small, ground-level herbivores.  During the first half of the Cenozoic, enigmoceratopsids diversified into dozens of species.  By the present time, the clade has withdrawn completely into a single species living in southeast Asia.

(Text by Daniel Bensen)

SAMPLE TAXA:

• Enigmoceratops

 

 

FURCICERATOPSIDAE

         Furciceratopsidae is an offshoot of the Asian protoceratopsia that has developed a graviportal body-form and ornate neck-frills similar to the extinct ceratopsids.  This clade was quite prolific even as late as the Pliocene, but the Ice Age has killed off all but the species of southern Asia.

(Text by Brian Choo and Daniel Bensen)

SAMPLE TAXA:

• Indian Megahorn

BRACHIOCERATOPSIDAE

    While some protoceratopsians continued evolving along the same lines as their Cretaceous neaceratopsian cousins, some Asian forms branched off to fill different niches. The largest surviving group are the brachioceratopians that started off as living at forest edges, and eventually evolved into high-browsers convergent with sauropods (or indricotheres). Brachioceratopians' heads became smaller and lighter, and their neck frills became smaller. (However they did evolve short blunt horns above the eyes.) Their necks became long but remained sturdy, and their legs became long and columnar, especially the forelimbs, that in most species are nearly as long as the rear limbs.

    Some brachioceratopsid forms (genus Titanoceratops) grew as large as their sauropod counterparts, but by the early Pliocene these giants had died out.

(Text by Matti Aumala and Daniel Bensen)

SAMPLE TAXA:

• Dwarf undaur
• Greater undaur
• Balundaur

POTAMOCERATOPSIDAE

    Behemoths (clade Potamoceratopsidae) probably share a common ancestor with the brachioceratopians (see above), though their evolution has taken a very different direction. Herds of behemoths roam the bottoms of rivers and lakes of Southern Asia, where neither titanosaurs of Africa nor aquatic nodosaurids of North America have spread.

(Text by Matti Aumala)

SAMPLE TAXA:

• Indian river behemoth