So far the greates success seems to be the 2003 Pyrenean ibex cloning project. It aimed to resurrect the extinct subspecies using frozen skin samples from the last known individual, which died in 2000. The project was led by Jose Folch of the Center for Agro-Nutrition Research and Technology in Aragon, Spain. The team used a technique called nuclear transfer to extract DNA from the skin samples and implanted embryos into 57 surrogate goats. The project resulted in seven pregnancies and one live birth, though the cloned calf died minutes after birth due to severe lung defects.

The resurrected species should be able to mate and give birth to fertile offspring for this to count. They should be genetically very similar to the extinct species.

The Pyrenean ibex are a subspecies of a species alive today which is far enough to count for this market. Dog breeds are too close to count (and so far there were no attempts to de-extinct any dog breed). More specific resolution criteria suggestions are welcome.

Cloned animals often have a variety of defects in vital organs such as the liver, brain, and heart, as well as issues with their immune systems. During the cloning process, epigenetic reprogramming can sometimes be incomplete, leading to errors in gene expression and regulation. When a clone is created from an adult cell, it may inherit shortened telomeres. Additionally, the Pyrenean ibex population experienced a decline in genetic diversity before extinction and struggled with factors such as disease, infertility, and inbreeding, which could have contributed to the lung problems in the cloned calf.