J430 - Finest Quality Large Triceratops horridus three-horned Dinosaur Tooth - Late Cretaceous - Lance Fm

Triceratops horridus from the Lance Formation refers to fossils of the iconic three-horned dinosaur found in the Late Cretaceous rocks of Wyoming and surrounding areas, often characterized by its longer snout and brow horns compared to T. prorsus, representing a common, earlier form in the dinosaur's evolutionary lineage before the later prorsus emerged just before the K-Pg extinction.

These fossils, including teeth, horns, and bone fragments, are key to understanding Triceratops evolution, with horridus showing features like a short nasal horn and forward-angled brow horns, distinct from its descendant. 

Key Information:
Triceratops horridus: One of the two recognized species of Triceratops, known for its distinctive "three-horned face," herbivorous diet, and large frill used for defense or display.

Lance Formation (L Fm.): A geological unit in the western United States (Wyoming, Montana, Dakotas) famous for its rich Late Cretaceous fossils, including many Triceratops specimens, dating to around 66 million years ago.

Physical Characteristics: T. horridus typically has a more elongated snout and brow horns that point forward and slightly outward, distinguishing it from T. prorsus, which has a shorter face and more upright brow horns.

Evolution: T. horridus is considered an ancestral species, evolving into T. prorsus in a linear fashion (anagenesis) just before the non-avian dinosaurs died out.

 
Significance:
Fossils from the Lance Fm. provide critical evidence of Triceratops' appearance, behavior (e.g., feeding, social behavior), and its final evolutionary stages. 
In essence, "Triceratops horridus Lance Fm" describes fossils of the classic Triceratops found in a specific, fossil-rich geological layer from the end of the dinosaur age, representing a significant species in the genus's lineage.