The observation that bats and dogs both possess fur, similar body sizes, and, in the case of some bat species, a fox-like face, often leads to the question of a close biological relationship. Both of these diverse animal groups are mammals, meaning they share a common ancestor that lived millions of years ago. To understand the true connection between a bat (Order Chiroptera) and a dog (Order Carnivora), one must look closely at their place on the biological family tree. This taxonomic comparison reveals that despite their superficial similarities, bats and dogs are separated by significant evolutionary distance.
The Short Answer: Shared Ancestry as Mammals
The most immediate and highest-level answer to the question of relationship is that both bats and dogs belong to the Class Mammalia. This shared classification means they possess a set of defining characteristics that distinguish them from other vertebrates. All mammals, including the tiny Kitti’s hog-nosed bat and a large Great Dane, are warm-blooded and internally regulate their body temperature. They also nourish their young with milk produced by mammary glands and have hair or fur present at some point during their lives.
A specific biological feature uniting all members of the Class Mammalia is the presence of three small bones in the middle ear—the malleus, incus, and stapes—which are used to transmit sound vibrations. The common ancestor of all living mammals lived roughly 180 million years ago, establishing the shared heritage for both the bat and the dog lineage. While this confirms a distant relationship, the vast diversity within the Class Mammalia means this shared link is extremely broad.
The Major Taxonomic Divide
The evolutionary paths of bats and dogs diverged significantly at the level of the Order, a major taxonomic rank below Class. Bats belong to the Order Chiroptera, a group uniquely defined by their capacity for true, sustained flight, a trait not shared by any other mammal. This adaptation involves forelimbs that have been modified into wings, where elongated arm, hand, and finger bones support a thin, double-layered skin membrane called the patagium. Many bats also possess the specialized ability of echolocation, using high-frequency sounds to navigate and hunt in the dark.
Dogs and their relatives, such as wolves, cats, and bears, belong to the Order Carnivora, a group primarily characterized by adaptations for predation. The defining feature of carnivores is their specialized dentition, which includes prominent canine teeth and a pair of carnassial teeth used for shearing meat. The evolutionary focus for carnivores centered on developing speed, strength, and specialized hunting behaviors rather than the radical skeletal changes required for flight. The unique physical demands and ecological niches of each Order led to a profound separation in their evolutionary trajectories.
Where Bats Sit on the Mammalian Family Tree
Modern genetic analysis provides the most accurate picture of their relationship, placing both dogs and bats within the superorder Laurasiatheria, a vast group of placental mammals. This superorder also includes animals such as whales, horses, and pangolins, meaning that bats are genetically as close to a horse or a whale as they are to a dog. The Laurasiatheria clade was established through DNA sequencing, as no obvious anatomical features unite all its diverse members.
Within the Laurasiatheria, dogs belong to the Ferae group (Carnivora and Pangolins), while bats belong to the Chiroptera. The two groups separated very early in the superorder’s history. This early split means that while they are related through a common ancestor in Laurasiatheria, they are more like extremely distant cousins. Bats are sometimes genetically grouped with the odd-toed ungulates (like horses and rhinos) as a sister taxon, or with a group called Ferungulata, which includes carnivores and ungulates, demonstrating the complexity of their deep evolutionary ties.
The visual similarity of certain “flying foxes” or fruit bats to dogs is a clear example of convergent evolution. This is where unrelated species evolve similar external features to adapt to comparable environmental pressures. The elongated snout and larger eyes of these bats are adaptations for their fruit-eating diet and reliance on vision, rather than a sign of recent shared ancestry with the Order Carnivora. The earliest known bat fossils, dating back over 50 million years, already possessed fully formed wings, confirming that the bat lineage diverged and specialized early in mammalian history.