#structural anatomy

• Allosaur — A large bipedal carnivorous dinosaur from the order Saurischia (genus Allosaurus) that lived during the Late Jurassic period. This top structural predator was characterized by a massive skull equipped with serrated, sharp teeth, powerful hind limbs, and relatively short forelimbs provided with three sharp claws, being one of the most studied fossil reptiles.
• Allosaur — An alternative spelling form or Romanian phonetic variant for allosaur; a large bipedal carnivorous dinosaur from the order Saurischia (genus Allosaurus) that dominated terrestrial ecosystems during the Late Jurassic period. This predator was structurally characterized by a massive skull equipped with long, serrated teeth, muscular hind limbs, and forelimbs provided with curved, sharp claws.
• Alveolus — An alternative masculine form, rarely used in current Romanian, for the feminine noun 'alveolă'; a small natural cavity, structural hollow, or cell formed in an organ, organism, or material. It appears sporadically in older medical literature or technical translations where the masculine gender from the Latin etymon 'alveolus' was preserved.
• Amphibiology — A specialized branch of zoology that deals with the multidisciplinary, systematic, and structural study of amphibians (class Amphibia), addressing aspects related to their anatomy, physiology, evolution, ecology, and geographical distribution. In modern academic terminology, this field is often integrated into or equated with herpetology (which combines the study of both amphibians and reptiles).
• Amphiphloic — Having or characterized by the presence of phloem tissue on both sides of the xylem; an adjective used in plant anatomy to define a structural type of central cylinder (amphiphloic siphonostele or solenostele), commonly found in ferns, where the central pith is successively surrounded by an inner ring of phloem, a central ring of xylem, and an outer ring of phloem.
• Amphineuran — A primitive marine mollusk belonging to the class Amphineura (in classical classifications), characterized by perfect bilateral symmetry, a structural nervous system composed of two pairs of longitudinal cords united by commissures, and a shell consisting of eight articulated calcareous plates (such as chitons) or a vermiform body lacking a shell. As an adjective, it describes an anatomical feature or an organism associated with this group.
• Lancelet — A small (a few centimeters), primitive marine vertebrate with a translucent, elongated body pointed at both ends, belonging to the phylum Cephalochordata. This structural organism represents an essential evolutionary transition link, as it retains the notochord, neural tube, and pharyngeal slits throughout its entire life, serving as a classic model in the study of comparative chordate anatomy.
• Amphioxus — A variant graphical form, directly borrowed from the Latin or English scientific nomenclature, for the standard Romanian noun 'amfiox'. It identifies the same small marine animal from the subphylum Cephalochordata, widely utilized in international academic literature and evolutionary biology university textbooks.
• Androtomy — An old medical term or scientific archaism historically used to designate the dissection of the male human body or the structural anatomical study focused exclusively on male-specific organs and systems. In contemporary clinical terminology, it has been entirely integrated into and replaced by the modern branches of andrology, urology, and human anatomy.
• Annelids — A major phylum of bilaterally symmetrical invertebrate animals (Annelida), comprising segmented worms such as earthworms, leeches, and marine polychaetes. Structurally, their body is characterized by homonomous metamerism, being divided externally and internally (by transverse septa) into a series of repeating ring-like segments, possessing a closed circulatory system and a ventral ganglionic nerve cord.
• Antitropic — Exhibiting inverse symmetry, situated in direct structural opposition, or having physical and geometric properties oriented in the opposite direction relative to a reference element. In anatomy, it describes paired organs or structures facing each other in opposite planes; in crystallography, it refers to symmetrically inverted crystalline axes or faces.
• Anthracothere — A fossil ungulate mammal belonging to the family Anthracotheriidae, structurally related to modern hippopotamuses and pigs, which lived during the Eocene and Oligocene epochs, whose skeletal remains have been frequently discovered within geological layers rich in lignite and fossil coal. This large-bodied animal possessed a specific bunodont dentition and short limbs adapted to aquatic or swampy environments, being an essential stratigraphic benchmark for dating carboniferous deposits.
• Sea urchin — The common name for marine invertebrates of the class Echinoidea, with a spherical, discoidal, or oval body covered in a calcareous exoskeleton equipped with numerous mobile spines. These organisms inhabit the sea and ocean floors, feeding mainly on algae, and play a structural role in coastal marine ecosystems.