I did the math to find the 5E CR for all the existing 2E athasian monsters. A CR / type list could help any Dark Sun DM to skin (suggested base for skin are in bracket) and rebuild those terrors for 5E 
Monstrosity
1/8 Silt Spawn [Octopus]
1/2 Xerichou
1 Bog Wader
1 Floater
1 Id Fiend
1 Cilops
2 Baazrag: Boneclaw [Giant Boar]
2 Silt Horror, Black
3 Tembo [Dire Wolf]
3 Pakubrazi [Doppelganger]
4 Jozhal
4 Silk Wyrm
4 Fordorran
5 Gaj
5 Chn’thrang
5 Flailer
5 Silt Horror, Red
5 Spinewyrm
6 Aviarag
6 Mastyrial, Black
7 Megapede
8 Silt Horror: Brown [Giant octopus]
8 Silt Horror, Magma
9 Dune Reaper: Warrior
9 Klar
10 Silt Horror: White
10 Sink Worm
12 Roc, Athasian Roc
12 Silt Horror: Gray
12 Drik
12 Drik, High
13 Cistern Fiend
13 So-ut (Rampager)
13 Mastyrial, Desert
14 Sand Vortex
16 Nightmare Beast
17 Cloud Ray
Undead
1/4 Kragling, lesser
1 Kragling, greater
1 Zombie, Thinking [Zombie]
2 Dhaot Ghost
3 Fael
4 Banshee, Dwarf [Banshee]
5 Feylaar
5 Racked Spirit
5 Wraith, Athasian [Wraith]
6 Raaig
8 Krag [Mummy]
13 T’liz
18 Meorty [Mummy Lord/Vampire]
18 Kaisharga [Lich]
Beast
0 Animal, Household: Renk
0 Animal, Household: Ock’n
0 Animal, Domestic: Mulworm
0 Animal, Household: Hurrum
0 Animal, Domestic: Aprig
1/8 Animals, Domestic: Kank [Mule]
1/8 Animal, Household: Critic [Lizard]
1/8 Animal, Herd: Jankz
1/8 Animal, Domestic: Sygra
1/8 Kes’trekel [Vulture]
1/8 Animals, Domestic: Erdlu [Axe Beak]
1/8 Wezer: Worker [Giant wasp]
1/8 Animal, Herd: Kip [Goat]
1/8 Insect Swarm: Locusts [Swarm of insects]
1/8 Insect Swarm: Mini-kanks [Swarm of insects]
1/8 Baazrag
1/8 Spider, Silt [Spider]
1/4 Wezer: Soldier [Giant wasp]
1/4 Animal, Herd: Z’tal
1/4 Antloid, Desert: Worker
1/4 Erdland [Axe Beak]
1/4 Rasclinn
1/4 Zhackal [Jackal]
1/4 Gorak
1/4 Jhakar [Crocodile (for bite)]
1/4 Kank, Wild [Mule]
1/4 Animal, Domestic: Carru
1/4 Scorpion, Gold [Scorpion]
1/2 Kluzd [Giant poisonous snake]
1/2 Wezer: Brood Queen [Giant wasp]
1/2 Antloid, Desert: Dynamis
1/2 Beetle, Agony [Giant fire beetle]
1/2 Cat, Psionic: Tagster [Tiger]
1 Antloid, Desert: Soldier
1 Cat, Psionic: Tigone [Saber-toothed tiger]
1 Pterrax Pteranodon
1 Razorwing [Giant Vulture]
1 Crodlu [Horse, riding]
1 Lirr
1 Sand Howler
2 Animals, Domestic: Inix [Giant crocodile]
2 Kirre [Saber-toothed tiger]
3 Antloid, Desert: Queen
3 Spider, Dark
3 Spider, Mountain
4 Spider, Crystal
4 Dagorran
5 Pulp Bee [Giant wasp]
5 Sloth, Athasian
5 Crodlu, Heavy [War horse]
6 Ruktoi
6 Scorpion, Barbed [Giant scorpion]
7 Dune Reaper: Drone
9 Animals, Domestic: Mekillot [Elephant]
Aberration
7 Psurlon
12 Psurlon, Adept
14 Stalking Horror (Moonbeast)
15 Psurlon, Giant
Construct
1/2 Psionocus [Homunculus]
5 Golem: Sand [Flesh Golem]
6 Golem: Ash
6 Golem: Chitin
6 Golem: Rock [Stone Golem]
6 Golem: Wood
7 Golem, Salt
10 Golem, Magma
12 Golem: Obsidian [Stone Golem]
12 Retriever, Obsidian
Dragon
10 Drake, Rain
10 Drake, Silt
12 Drake, Magma
16 Drake, Sun
19 Drake, Fire
19 Drake, Water
20 Drake, Earth
20 Drake, Air
29 Dregoth
30 Dragon of Tyr
Elemental
6 Elemental Beast, Air
6 Elemental Beast, Earth
6 Elemental Beast, Fire
6 Elemental Beast, Water
6 Paraelemental Beast, Magma
6 Paraelemental Beast, Rain
6 Paraelemental Beast, Silt
6 Paraelemental Beast, Sun
6 Ruvoka: Ethilum
11 Ruvoka: Brajeti
12 Ruvoka: Kaltori
15 Ruvoka: Zathosi
18 Spirit of the Land
Giant
1 Half-Giant [Half-Ogre]
2 Dune Freak (Anakore)
2 B’rohg
8 Braxat
9 Giant: Desert
10 Giant: Beasthead
11 Giant: Plains
12 Giant, Shadow
Humanoid
1/8 Silt Runner [Kobold]
1/8 Hej-kin [Goblin]
1/8 Tarek [Orc]
1/4 Tari [Troglodyte]
1/4 Gith [Grimlock]
1/4 Pterran [Lizardfolk]
1/4 Nikaal [Lizardfolk]
1/2 T’Chowb
1/2 Ssurran [Lizardfolk]
1/2 Tul’k
1 Slig
1 Villichi [Acolyte]
2 Belgoi
2 Scrab
4 Thri-kreen [Thri-kreen]
4 Tohr-Kreen: J’ez [Thri-kreen]
4 Tohr-Kreen: J’hol [Thri-kreen]
4 Tohr-Kreen: T’Keech [Thri-kreen]
4 Tohr-Kreen: Tondi [Thri-kreen]
5 Thrax
5 Tohr-Kreen (Mantis Noble) [Thri-kreen]
12 Trin [Thri-kreen]
15 Pyreen
15 Pyreen: Alar Ch’Aranol