As is shown in the show, ponies aren't the only creatures who have marks, but most of those who do have marks are pony-adjacent, like zebra. In one of my more extensive RPs, I discuss the concept of similar events to receiving a cutie mark for other sentient species and how this relates to their own coming of age. (Specific section)

In this blog post I'll summarize some of what I put down there and what I can remember for the types not mentioned in that RP, splitting the species into a few different posts as to keep these entries from getting too long. If there's a creature you're very interested in seeing, please comment or message me so I can add them to the list.

As a disclaimer, I'm not basing any of the following information off of any show canon, this is pure fanon that I believe has no conflicts with the show and should work well for anyone wanting to play a character of these species.

Camels

Camels are a mostly nomadic species found in the San Palomino desert south of the Mild West, and scattered about the deserts of Zebrica. They mostly roam in small family units, similar to the buffalo but often smaller groups. Their culture is focused mostly on the sands and the oases, their natural magic being a form of geomancy that allows them some control over the sand they walk on, making crossing the desert and caring for their oases an easy task.

When a young camel receives a mark, it is not so much a mark on their bodies but one left behind when they rise up after a long rest, an effect caused by their natural magics shifting the sand beneath them. Like zebra, these marks are often abstract concepts with many wavy lines that often don't mean much on their own or to an outsider. This mark will then appear whenever the camel rests and is left behind when they leave.

Upon noticing that they have left a mark, the camel's family will travel to the nearest oasis to meet with the local sand speaker, which is their equivalent to a zebra elder or shaman, who will interpret their mark and lead the young camel in a writing ritual to formalize the mark. A tent is erected in the sand to shield an area from wind and sun, and the sand speaker makes a larger version of the young camel's mark. The camel then writes in and between the lines of their mark their own understanding of it, along with their hopes and dreams, and fears for the future. Once they are done writing, the tent is removed and the wind allowed to erase the writings, symbolizing that the desert will hold their secrets and aid them to come to fruition.

Diamond Dogs

Diamond dogs do not have marks, nor much in the way of natural magics, but they still come of age and have some magic to guide them in their journey. From a young age dogs are taught to be self-reliant and how to survive in the wild. Once a dog is old enough, as determined either by their parents, the den leader, or their own volition, they leave the den in search of their own mineral. Dogs on this journey are to live on their own, without outside help, but they are allowed to form a pack with other young journeying pups if they are so lucky as to encounter others.

After some time they will find a gem or mineral that resonates with them, often, but not always, it is the first one they find a good amount of. At this point the dog will make a choice either to return to their home den, join a new den, or build their own den and form a pack from those they traveled with. Historically, dogs would bring the mineral or gem they found to an elder for it to be interpreted, but few dogs today put much stock into old prophecies so it is becoming a rarer occurrence. Typically a dog will choose to name themselves after the gem or mineral they found, like Amber Shepherd, Gypsum Pointer, etc.

Deer

Deer are an example of how gender dimorphism affects both magic and coming of age. Among deer, only the males grow antlers, and they only have antlers seasonally, meaning that they are only able to effectively cast spells for part of the year. They are not entirely without magic when their horns are not present however, but that can be discussed in a dedicated Species post.

Bucks

Male deer grow antlers at the start of Spring after about 8-12 years of life (Adjusting normal deer lifespan to make it the same length as ponies) and they fall off towards the end of Fall. When a fawn grows his first antlers, those in his glen will watch for when his magic fully develops, which culminates in a First Spell. This first use of magic is often wild, but reveals the buck's natural talents and desires. This will lead the buck to be presented to a mentor capable of guiding them in fully developing their skills until they become a full adult.

Does

Female deer do not grow antlers, instead their natural magics are directed towards a guiding force which many call The Path or The Roots. This stems from a cultural belief in the great tree that binds all of nature together, and unites all creatures. It's roots stretch everywhere and guide those who seek it to what they desire. Most does only see the path when meditating, but some especially gifted does can use the path to guide them in combat or other intense activities, or can use it to locate creatures or items at great distances as well as knowing instinctively how to get there.

When a young fawn comes of age, she will see the path in her dreams for the first time, getting a look at all the ways her life could go and a few ideas as to which path she should take in life to achieve her desires. It is an unmistakable experience for a young doe, though there may be a few false starts before it happens. After the dream occurs, the young doe will be presented to an elder well versed in the path, or one will arrive at their glen having been guided there by the path. This elder will guide them through meditative exercises in order to better see the path while it is fresh, and teach them how to use it in their lives going forward.

Together

Due to the gender dimorphism, young bucks and does will often pair up soon after coming of age, each one using their gifts to compliment the other. This starts out as simple friendships, often forming into groups of 3-5 for the first few years, before officially pairing off once they've more fully matured.