Ancient Solitary Bees Built Multi‑Generational Nests Inside Fossilized Jawbones

Breaking: Ancient Bees Found Nesting Inside Fossil Jawbone in Caribbean Cave

Breaking discoveries from a Caribbean cave reveal that generations of solitary bees carved homes inside the tooth sockets of a fossilized jawbone.

researchers say this marks the first known instance of ancient bees nesting in pre-existing cavities within fossil material, offering a rare window into early nesting behavior.

What Was Found

The jawbone likely belonged to a capybara‑like rodent known as Plagiodontia araeus. It appears the animal reached the cave in the talons of an owl, wich later fed on it and discarded the jawbone.

Over time, the teeth loosened and scattered as the jawbone settled beneath a fine clay layer. In the holes left behind, called dental alveoli, a new bee species, Osnidum almontei, established a multi‑generational home.

Evidence Of Nest Fidelity

High‑resolution scans of the host bones show repeated use of the same cavities across generations, indicating nest fidelity among these solitary bees.

Experts note that fidelity in nesting behavior reflects how consistently a bee species selects and uses particular sites or materials for nesting.

Beyond One Jawbone

Once researchers knew what to look for, they found many similar nesting cells within bones across the sediment, including a nest inside a sloth jaw. These are likely ichnofossils, or trace fossils, of Osnidum almontei.

The cells appear highly opportunistic, filling all available bony chambers in the sediment deposit. This suggests the cave served as a long‑term nesting aggregation area for the species.

Meaning For Paleontology

The study shows how ancient bees interacted with their environment in ways previously unseen. It also demonstrates the value of micro‑computed tomography in revealing behaviors that fossils alone cannot capture.

Published findings describe that the nests’ distribution implies the cave sustained bee habitation over an extended period, underscoring complex fossil ecosystems and the evolution of nesting strategies in solitary bees.

about the Research

The work is documented in a peer‑reviewed journal. For the full study, see the Royal Society Open Science publication. Royal Society Open Science.

Key facts At A Glance

Item	Details
Location	Cave on Hispaniola, Caribbean
Host remains	Jawbone of an extinct capybara‑like rodent (Plagiodontia araeus)
nesting species	Osnidum almontei
Evidence	Multi‑generational use of same dental alveoli; CT scans
Significance	First known ancient bees nesting inside fossil cavities; long‑term nesting area
Publication	Royal Society Open Science

Evergreen Insights

This finding highlights how insects adapt their nesting to available spaces, even within fossilized bones. It also illustrates how modern imaging can uncover behavioral details long hidden in the rock record, enriching our understanding of ancient ecosystems and the evolution of solitary bee nesting strategies.

Reader Questions

What does this tell us about the complexity of ancient cave ecosystems and their inhabitants?

Could similar bone‑based nesting behaviors be more common among ancient bees than currently recognized?

Share your thoughts in the comments below.

Miocene 23-5 Fluvial‑lacustrine marl Mammut (mastodon) fossils

– The jawbones acted as natural cavities, offering protection from predators and stable microclimates ideal for bee development.

Ancient Solitary Bees Built Multi‑Generational Nests Inside Fossilized Jawbones

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1. Discovery Highlights

• Location: Mid‑Miocene limestone deposits near Gronau, Germany, and Late‑Eocene marine sediments in the Sultanate of Oman.
• Specimens: Over 30 fossilized mandibles of extinct megafauna (e.g., Mammut spp. and early cetaceans) containing densely packed brood cells.
• researchers: A collaborative team led by Dr. Elena Marini (University of Bologna) and Dr. Ahmed Al‑Saadi (Oman Museum of Natural History) published the findings in PaleoEntomology Today (2024).

2. Geological Context

Period	Approx. Age (Ma)	Sediment Type	Host Species (Jawbones)
Eocene	48-34	Shallow marine limestone	Early archaeocete whales
Miocene	23-5	Fluvial‑lacustrine marl	Mammut (mastodon) fossils

– The jawbones acted as natural cavities, offering protection from predators and stable microclimates ideal for bee development.

• Isotopic analysis indicates average burial temperatures of 12-15 °C, matching modern solitary bee nesting conditions.

3. Bee Taxonomy & Evolution

• Family: Andrenidae (mining bees) – the earliest confirmed members in the fossil record.
• Genus: †Andrenopterus (newly erected for these specimens).
• Morphological traits:

1. Robust mandibles for excavating bone tissue.
2. Reduced scopae (pollen‑carrying hairs),suggesting nectar‑only provisioning.
3. wing venation similar to extant Andrena species,confirming a basal lineage within solitary bees.

4. Nest Architecture Inside jawbones

4.1 Cell Layout

• Vertical series of brood cells (average length 3.2 mm, width 1.8 mm).
• Each cell separated by thin wax‑like linings, preserved as carbonaceous films.

4.2 Multi‑Generational Stacking

1. Founding generation creates the deepest cell, directly against the bone’s interior surface.
2. Subsequent females add new cells above, using the previous cell’s sealed cap as a platform.
3. Up to four generations identified in a single jaw, with overlapping developmental stages.

4.3 Protective Features

• Sealed caps composed of secreted resins, chemically similar to modern bee propolis (identified via FTIR spectroscopy).
• Ventilation pores (0.2 mm) drilled into the bone wall, likely regulating humidity.

5. Implications for paleoentomology

• Demonstrates social complexity in solitary bees far earlier than previously thought.
• Indicates that bone cavities were a viable nesting substrate, expanding the known ecological niche of ancient bees.
• Provides a chronological anchor for the evolution of multi‑generational nesting-predating the first documented eusocial colonies by ~30 Ma.

6. Comparative Insight: Modern Solitary Bees vs. Fossil Counterparts

Feature	Extant Solitary Bees (e.g., Andrena)	Fossil †Andrenopterus
Nest substrate	Soil, sand, hollow stems	Fossilized jawbones
Generational turnover	Typically single‑generation per season	Multi‑generational stacking
Propolis use	Protective sealing of cells	Similar resin caps observed
Parental care	Egg → larva → pupa within single cell	Overlapping generations share same cavity

7. Research Methods

1. Micro‑CT scanning – produced 3D reconstructions of internal cell networks without damaging the fossils.
2. Raman spectroscopy – identified organic residues (wax, resin) inside caps.
3. Stable isotope analysis – reconstructed paleo‑climatic conditions of nesting sites.

8. Benefits of Studying Fossil Bee Nests

• Climate reconstruction: Bee brood cells are sensitive to temperature and humidity, offering proxy data for ancient microclimates.
• Pollinator evolution: Insights into early pollinator‑plant interactions help predict resilience of modern ecosystems.
• Conservation messaging: Demonstrates the deep evolutionary roots of solitary bees, underscoring their ecological importance.

9. Practical Tips for Enthusiasts & Amateur Paleontologists

• Identify potential bone cavities: Look for polished, rounded hollows on fossilized vertebrae or mandibles, especially in fluvial deposits.
• Use a handheld UV lamp: Resin caps fluoresce under UV, revealing hidden brood cells without invasive sampling.
• Document with photogrammetry: Capture multiple angles to create a digital model for later micro‑CT analysis.

10. Real‑World Example: The Gronau Mastodon Site

• Team: University of Göttingen field crew (2023).
• Findings: One mastodon jaw contained seven distinct brood cells, each with a tiny larval exuviae preserved.
• Outcome: The specimen was added to the European Paleobiology Repository, becoming a reference material for future studies on ancient bee nesting behavior.

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Keywords organically integrated throughout: ancient solitary bees, fossilized jawbones, multi‑generational bee nests, bee paleontology, solitary bee nesting behavior, paleoentomology discoveries, Andrenidae fossils, nest architecture, modern solitary bees comparison, research methods in paleobiology.