Do natural melee weapons (from racial traits) trigger Improved Divine Smite?

Question

Following up on Does Improved Divine Smite trigger when a paladin makes an unarmed strike?

Improved Divine Smite will not trigger on an unarmed strike.

Context

The paladin in my campaign – covered in my previous question – is a minotaur. This means he could attack with his horns, to potentially trigger Improved Divine Smite.

Minotaur, Unearthed Arcana: Centaurs and Minotaurs:

Horns. Your horns are natural melee weapons, with which you’re proficient. When you hit with them, the target takes piercing damage equal to 1d6 + your Strength modifier.

Paladin, PHB page 85:

Improved Divine Smite. By 11th level, whenever you hit a creature with a melee weapon, the creature takes an extra 1d8 radiant damage.

Question

Do natural melee weapons from racial traits trigger Improved Divine Smite?

In other words, do natural weapons count as melee weapons? Or is there some other rule that categorizes/treats natural melee weapons differently from other melee weapons?

For my campaign I'm mostly interested in the natural melee weapon from minotaurs. I'm assuming, however, the same rules would apply for other natural melee weapons gained through racial traits – e.g. a lizardfolk's Bite, tabaxi's Claw, centaur's Hoove, etc. If this assumption is wrong, please enlighten me.

Answer 1

Yes, if the racial rule calls them weapons

(This answer has been updated to reflect the apparent shift in the wording of the rules since Explorer's Guide to Wildemount. The original answer is below the horizontal rule.)

User Mavoc points out that the wording for most of the races with natural weapons has been revised. The online version of those races (and printed versions since Explorer's Guide to Wildemount) uses slightly different wording from previous publishings:

Your talons are natural weapons, which you can use to make unarmed strikes.

Further, it seems this wording change "which you can use to make unarmed strikes" has ben retroactively applied to virtually all races that have natural weapons on D&D Beyond.

For context, the PHB (page 119) states:

Instead of using a weapon to make a melee weapon attack, you can use an unarmed strike: a punch, kick, head-butt, or similar forceful blow (none of which count as weapons).

So, while general rule that unarmed strikes can't work with Improved Divine Smite because unarmed strikes aren't weapons, the rule for races like the Aarakocra, specifically says that the relevant anatomy is a natural weapon. This would allow it to work with abilities that require a weapon despite the fact that an unarmed strike is being made.

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As your other linked answer states, Unarmed Strikes do not work for Improved Divine Strike because the rules say Unarmed Strikes are not weapons:

Instead of using a weapon to make a melee weapon attack, you can use an unarmed strike: a punch, kick, head-butt, or similar forceful blow (none of which count as weapons).

But the racial ability for Minotaur horns specifically says the horns are a weapon:

Your horns are natural melee weapons

What is happening here is that there is a specific rule/allowance for the Minotaur that is similar to (but different from) a general prohibition.

The minotaur is not making an Unarmed Strike (a head-butt). It is making an attack with a weapon which happens to be located on its head.

Contrast this with the Aarakocra's Talons:

Talons

You are proficient with your unarmed strikes, which deal 1d4 slashing damage on a hit.

(Hat tip to Justin for the Aarakocra example)

Also, Jeremy Crawford has tweeted an affirmation of this answer.

Answer 2

Yes, if it says they are weapons

The Minotaur race Horns racial feature says (emphasis mine):

Your horns are natural melee weapons, with which you’re proficient. When you hit with them, the target takes piercing damage equal to 1d6 + your Strength modifier.

Divine smite says:

By 11th level, whenever you hit a creature with a melee weapon, the creature takes
an extra 1d8 radiant damage.

So, in this case it is valid, as it says that your horns are weapons. However, this only applies to the Minotaur race. Racial attack abilities vary between races. For instance, the Aarakockra race's Talon racial feature says:

You are proficient with your unarmed strikes, which deal 1d4 slashing damage on a hit.

In this case, it does not say that the talons are weapons, and it therefore follows the 'it does not work' unarmed strikes path.

You can tell the difference between the racial attacks eligible for Improved Divine Smite, and those ineligible, as the valid ones say that it is a weapon, and the not valid ones don't.