Context: A lineal descendant, in legal usage, is a blood relative in the direct line of descent - the children, grandchildren, great-grandchildren, etc. of a person. In a legal procedure sense, lineal descent refers to the acquisition of estate by inheritance from grandparent to parent and parent to child, whereas collateral descent refers to the acquisition of estate or real property by inheritance from sibling to sibling, and cousin to cousin., A clade (from , "klados", "branch") is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life"., Reptiles are tetrapod (four-limbed vertebrate) animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology., Sauropsida ( `` lizard faces '' ) is a group of amniotes that includes all existing reptiles and birds as well as their fossil ancestors and relatives . Sauropsida is distinguished from Synapsida , which includes mammals and their fossil ancestors . This clade includes Parareptilia and other extinct clades . All living sauropsids are members of the sub-group Diapsida ., The superclass Tetrapoda (Ancient Greek s tetrapods, "four-footed"), or the tetrapods , comprises the first four-limbed vertebrates and their descendants, including the living and extinct amphibians, birds, mammals, reptiles and some ancient, exclusively aquatic creatures such as the Acanthostega. Tetrapods evolved from the lobe-finned fishes around 390 million years ago in the middle Devonian Period, with modern tetrapod groups having appeared by the late Devonian, 367.5 million years ago. The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear, and are areas of active research and debate among palaeontologists at present., In biology, an organism is any contiguous living system, such as an animal, plant, fungus, archaeon, or bacterium. All known types of organisms are capable of some degree of response to stimuli, reproduction, growth and development and homeostasis. An organism consists of one or more cells; when it has one cell it is known as a unicellular organism; and when it has more than one it is known as a multicellular organism. Most unicellular organisms are of microscopic scale and are thus loosely described as microorganisms. Humans are multicellular organisms composed of many trillions of cells grouped into specialized tissues and organs., Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the Cretaceous period, about 99 million years ago and diversified after the rise of flowering plants. More than 12,500 of an estimated total of 22,000 species have been classified. They are easily identified by their elbowed antennae and the distinctive node-like structure that forms their slender waists., Parareptilia ("at the side of reptiles") is a subclass or clade of reptiles which is variously defined as an extinct group of primitive anapsids, or a more cladistically correct alternative to Anapsida. Whether the term is valid depends on the phylogenetic position of turtles, the relationships of which to other reptilian groups are still uncertain., Subject: sauropsida, Relation: subclass_of, Options: (A) animal (B) biology (C) branch (D) cretaceous (E) family (F) formicidae (G) group (H) growth (I) hymenoptera (J) inheritance (K) insects (L) life (M) line (N) lineal descendant (O) node (P) person (Q) position (R) scale (S) sense (T) single (U) species (V) subclass (W) term (X) tetrapoda (Y) tree
Output: tetrapoda