How can an ancestor be extinct if its descendants are still around?
Extinction of an ancestral species means the original population's unique genetic lineage has ended, even if some of its genes persist in later species. The Tarpan, a wild horse that died out in the early 20th century, is a classic example. A 2026 study of 160 horse genomes (12 Polish Konik, plus modern breeds, ancient Polish horses, Przewalski horses, and Tarpan remains) found that Polish Konik horses share an ancestral component with ancient and primitive horse populations, but none of the analyses showed a closer relationship to the Tarpan than other breeds [1]. The Tarpan's specific genetic combination is gone, so it is extinct, even though its descendants carry some of its DNA.
The same logic applies to deeper evolutionary branches. A 2025 study of the early Palaeocene mammal Conoryctes comma (a taeniodont) notes that this group has 'no living descendants' [2]. Here extinction is absolute—the entire lineage died out. This contrasts with the Tarpan case, where the ancestor's genes survive in modified form. The key point is that extinction is about the loss of a distinct genetic lineage, not the total disappearance of all genetic material.
What does 'ancestral condition' mean when the ancestor is extinct?
Even when an ancestral species is extinct, scientists can reconstruct its traits by comparing its fossil remains with living descendants. A 2021 study of the stapes (a tiny ear bone) in extinct marsupial relatives (sparassodonts) and living marsupials found that a triangular stapes with a hole (intracrural foramen) and a rounded footplate is likely the ancestral condition for all marsupials [3]. This was determined by mapping the bone's shape onto the evolutionary tree—the extinct sparassodonts share this feature with many living marsupials, so it was probably present in the common ancestor. The ancestor itself is extinct, but its anatomical blueprint can be inferred.
This approach works because extinct species often preserve traits that are lost or modified in some descendants. The study examined stapes from three extinct sparassodont species and compared them with living caenolestids and microbiotheriids. The extinct forms showed the same basic design, allowing researchers to deduce the ancestral marsupial condition [3]. So extinction does not erase all information about an ancestor—fossils and comparative anatomy can reveal what it was like.
Can an ancestral species be so ancient that its 'extinction' is a matter of definition?
For the most ancient ancestors, like the Last Universal Common Ancestor (LUCA) of all life, extinction is not a simple yes/no. A 2021 study of tRNA methyltransferase enzymes (Trm5 in archaea, TrmD in bacteria) found that these proteins are not homologous—they evolved independently after the bacterial and archaeal lineages split [4]. This implies that LUCA had a high rate of translation errors (frameshifting), meaning it was still evolving the genetic code. The author argues that LUCA was a 'progenote'—a primitive, error-prone entity that does not fit the modern definition of a species [4]. In this view, LUCA is not 'extinct' in the same way a horse is; rather, it represents a stage of evolution that no longer exists because its descendants evolved more precise genetic machinery.
This deep-time perspective shows that extinction can be gradual and conceptual. The study notes that the absence of m1G37 methylation in tRNAs would have caused high +1 frameshifting errors, a hallmark of a still-evolving translation system [4]. So the 'ancestral species' (LUCA) is extinct not because its descendants died, but because the very nature of life changed—the error-prone state was replaced by more accurate systems. This is a different kind of extinction, one tied to the evolution of fundamental biological processes.
About These Sources
This answer is built on 5 peer-reviewed studies — published from 2021 to 2026, 2 from 2024 or later, 1 in Q1 journals — selected as the most relevant from 5 studies that passed quality screening, drawn from 54 papers retrieved from a database of over 500 million.
Sources used in this answer
Whole Genome Data Uncover the Complex Origins of Polish Konik Horses
A 2026 whole-genome study of 160 horse genomes (including 12 Polish Konik, ancient Polish horses, Przewalski horses, and Tarpan remains) found that Polish Konik share an ancestral component with ancient and primitive horse populations, but none of the analyses showed a closer relationship to the extinct Tarpan than other breeds, indicating the Tarpan's unique genetic lineage is lost.
Palaeohistology and life history of the early Palaeocene taeniodont <i>Conoryctes comma</i> (Mammalia: Eutheria)
A 2025 palaeohistological study of the early Palaeocene taeniodont Conoryctes comma found that this mammal had rapid growth to near adult size in one year and reached sexual maturity in one year, and notes that taeniodonts have no living descendants, making this an example of absolute lineage extinction.
The stapes of stem and extinct Marsupialia: implications for the ancestral condition
A 2021 study of the stapes bone in extinct sparassodonts and living marsupials found that a triangular stapes with an intracrural foramen and rounded footplate (stapedial ratio ~1.6-1.7) is likely the ancestral condition for Marsupialia, reconstructed from extinct and extant species.
Errors of the ancestral translation, LUCA, and nature of its direct descendants
A 2021 analysis of non-homologous tRNA methyltransferases Trm5 (archaea) and TrmD (bacteria) concluded that these enzymes evolved after the bacterial-archaeal split, implying that the Last Universal Common Ancestor (LUCA) had a high rate of translation errors and was a 'progenote'—a primitive evolutionary stage that no longer exists.
“Unoccupied And Of A Valuable Kind”/“Dry As The Blood Of Its Builders”
A 2021 historical analysis of the 'Cliff Dwellers' in late 19th/early 20th century popular archaeology shows that Euro-Americans often asserted these people were an extinct race with no connection to living Native groups, despite evidence of descendants, illustrating how cultural narratives can misrepresent extinction.