Organism · Placental mammals
Meniscomys hippodus
Source time context (not species duration) · ≈ 30–18 Ma
Inferred life reconstruction
Meniscomys hippodus
Overview
Meniscomys hippodus is a fossil rodent studied through jaws and teeth from John Day in the USA. Raised areas on its small molars help distinguish the species. It illustrates how a small fragment of upper jaw can become important evidence without an entire skull.[1]
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Key facts
The heights of raised tooth features were used for comparison. In 2021, a researcher described features intermediate between those of two other Meniscomys species. Even similar small teeth can reveal differences that distinguish species.[1]
Time and place
The upper jaw studied came from the Turtle Cove Member of the John Day Formation in the present-day USA. Fossil-bearing strata in the database are summarized as roughly 30–18 million years ago, spanning the Oligocene and Miocene. A specific upper jaw can be considered alongside records from several rock layers.[1][3]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
The principal material associated with the species consists of upper-jaw teeth. Comparative studies also discuss skulls of the genus Meniscomys and the body organization of early rodents.[1][2]
A study estimated a body mass of approximately 70 g. Starting with an upper jaw and tiny teeth, we can picture an ancient rodent that may have weighed tens of grams.[8]
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Habitat and reproduction
The author of a 2021 poster inferred a plant-based diet and a forest environment from the teeth. The height and shape of small molars led to questions about its way of life. Studies of skull form can be considered alongside interpretations of the ancient environment.[1]
Fossil discovery
The John Day upper jaw was compared with earlier descriptions in a 2021 undergraduate research poster. The researcher assigned it to this species by comparing its dental features with those of two other species. It illustrates the process of comparing a newly found small fossil with older literature.[1]
References
- Lisle (2021) — The Meniscomys upper jaw from John Day
- Hopkins (2005) — Comparing Meniscomys and early rodents
- Paleobiology Database — Stratigraphic records of Meniscomys fossils
- Lisle (2021) — The Meniscomys upper jaw from John Day
- Paleobiology Database — Stratigraphic records of Meniscomys fossils
- Barrett (2016) — Classification of North American nimravids
- Paleobiology Database — Stratigraphic records of Nimravus fossils
- Smits (2017), Remodeling the Fossil Record: Analysis of Emergent Evolutionary and Ecological Patterns
Research questions
What can tiny upper-jaw teeth reveal? Comparing the heights and shapes of raised features raises distinct questions about species identification and diet. The same fossil can be a starting point for research on both classification and life habits.[1]
Observation
Move your gaze from the broad outline of the head to the mouth and molars. Consider the whole body while remembering that research on this animal begins with tiny tooth shapes.[1][2]
Related organisms
Nimravus brachyopsPlacental mammalsSource time context (not species duration) · ≈ 32–18 MaTwo mammals in the North American rock record
Meniscomys and Nimravus are North American mammals introduced through summaries of Oligocene–Miocene strata. Compare the rodent upper jaw from the John Day Formation with the jaws and skulls of catlike Nimravus as different kinds of evidence.