Tooth architecture

Each tooth has a crown (the functional cutting/holding surface) and a root (the anchor). The crown is sheathed in enameloid—a hard, fluorapatite‑rich tissue—over dentine. In many fossil forms you’ll notice a darker, triangular band at the crown’s base called the bourlette (common in large lamniform sharks).

A living conveyor belt

Sharks grow multiple rows of teeth. New teeth develop inside the jaw and roll forward as older ones are lost. That’s why teeth are abundant as fossils while cartilage skeletons are rare.

Mineral swap

Original bioapatite persists but often trades ions with groundwater. Fluorine‑rich environments toughen the enamel; iron, manganese, and organic compounds tint crowns and roots.

Palette by sediment

• Jet/charcoal — phosphate sands, tannin‑rich rivers.
• Slate/steel grey — marine clays and limestones.
• Honey/russet — iron‑bearing sands.
• Bone‑tan — arid, carbonate‑rich settings.

Color reflects chemistry and burial—not simply age—so black doesn’t automatically mean “older.”

Tumbling & texture

River and surf polish can round roots and soften serrations; teeth from consolidated strata may keep crisp edges and a matte root texture.

Three feeding strategies

• Grasping: needle‑like, slender teeth for gripping fish and squid (many requiem sharks; sand tigers have long, curved daggers with small side cusplets).
• Cutting: triangular, flattened, often serrated blades for shearing (white shark lineage; the extinct giant Otodus (Megalodon) shows massive, broad triangles with stout roots).
• Crushing: pavement teeth, low domes forming mosaics for cracking shells (rays, guitarfish, horn sharks).

Field ID cues

• Serrations present? Think cutting specialists (coarse vs. fine serrations help narrow lineage).
• Side cusplets at the shoulders? Common in many Cretaceous and early Paleogene species.
• Root shape: deep V‑notch vs. broad U; lobes symmetrical or angled.
• Curvature: blade leaning strongly to one side often indicates lateral rather than anterior position.

Photo tip: Raking light makes serrations pop; a neutral grey card keeps enamel color honest.

Serration story

At 10×, cutting teeth show micro‑serrations that can be coarse, fine, or mixed near the tip. Rounded or worn serrations suggest transport.

Enameloid vs. root

The crown’s surface is smooth and glassy; the root is porous with tiny vascular pits. Repairs or restorations often look glossier than natural roots.

Bourlette & shoulders

In large lamniform teeth, a darker bourlette band sits between crown and root. The “shoulders” may carry cusplets—handy for age and family placement.

Ray dental plates

Appear as flat, polygonal tiles rather than pointed crowns; surfaces show a braided or pebbly texture from fused tooth elements.

Fish & reptile teeth

Bony fish teeth are often smaller, conical, and lack the distinct shark root lobes; mosasaur teeth are thicker, enamelled cones with visible growth lines and separate bony roots.

Cast replicas

Resin casts may show mold seams, uniform “plastic” gloss, and bubble pits. Natural teeth show differing textures between crown and root and subtle mineral staining.

Re‑sharpened “fantasy” teeth

Over‑polished serrations, unnatural symmetry, or a glossy root can signal heavy reworking. A loupe is your best truth‑teller.

Mako vs. white shark

Mako teeth: unserrated, sleek triangles. White shark: serrated blades with strong shoulders. Simple, useful distinction.

Quick checklist

• Glassy crown + porous root? → fossil tooth, not glass.
• Serrations crisp and consistent? → cutting specialist lineage.
• Tiles/pavement? → ray plate, not a shark cusp.

Where they’re found

Abundant in marine sediments and reworked river gravels. Notable hunting grounds include the Atlantic Coastal Plain of the USA (beaches & rivers), phosphate mines of Morocco, North Sea dredge spoils, and many coastal cliffs and quarries worldwide. After storms or seasonal low water, fresh finds appear.

Time travel in a tray

Micro‑teeth sieved from sands can span millions of years in one pan—Cretaceous needles, Paleogene cusplets, Neogene blades. Label by formation + age + locality and your tray becomes a tidy timeline.

Finding methods

• Beachcombing: scan the shell line; teeth sparkle like tiny black triangles among fragments.
• River screening: shovel gravel into a sifter; gentle swishing reveals glossy crowns.
• Micro‑teeth: dry sand on a white tray and swirl—dark specks with a triangular glint are candidates.

Cleaning basics

• Soak in lukewarm water + mild soap; use a soft brush.
• Avoid acids (can etch) and harsh bleach (can chalk roots).
• Stubborn matrix: wooden toothpick or bamboo skewer; patience beats abrasion.

Stabilizing & display

• Fragile roots can be consolidated with a reversible acrylic such as a thin B‑72 solution.
• Shadow boxes with a neutral backing make serrations stand out.
• Note any restoration on your label—future you will thank present you.

Serration spotlight

Hold a small flashlight at a low angle across the edge. Micro‑serrations cast tiny shadows you can count—great for comparing species.

Root vs. crown

Touch the tip to your lip (carefully): the crown feels glass‑cool, the root more chalk‑warm. Texture tells you where enamel ends and dentine begins.