(a.) Of or pertaining to a division of the Silurian formation, corresponding in general to the Lower Silurian of most authors, exclusive of the Cambrian.
(n.) The Ordovician formation.
Example Sentences:
(1) Furthermore, the identification of vertebrate hard tissues in the oral elements of conodonts extends the earliest occurrence of vertebrate hard tissues back by around 40 million years, from the Middle Ordovician (475 million years ago) to the Late Cambrian (515 million years ago).
(2) His message remains blunt today: “Show me a scientist who claims there is no population problem and I’ll show you an idiot.” Earth’s five previous mass extinctions End-Ordovician, 443 million years ago A severe ice age led to sea level falling by 100m, wiping out 60-70% of all species which were prominently ocean dwellers at the time.
(3) – Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous … 'What will survive of us is love', wrote Philip Larkin.
(4) It begins with a discussion of the origins of the craniofacial tissues in the dentine and bone of the dermal denticles of the Ordovician jawless vertebrates, followed by a brief discussion of the mechanisms responsible for the evolution of the jaws and the origin of vertebrate dentition.
(5) In each of the following, more than half the Earth’s species disappeared: 1 End-Ordovician, 443 million years ago.
(6) Paleontological data indicate that the earliest recognizable vertebrate remains, bone fragments of Upper Cambrian and Lower Ordovician heterostracan fishes, were deposited in a marine situation.
(7) Dentine, the bone of attachment associated with dentine, the basal bone to which dermal denticles are fused and cartilage of the Ordovician agnathan dermal exoskeleton were all derived from the neural crest and not from mesoderm.
(8) Cartilage (unmineralized) can be inferred to have been present in heterostracans and osteostracans, and globular mineralized cartilage was present in Eriptychius, an early Middle Ordovician vertebrate unassigned to any established group, but assumed to be a stem agnathan.
(9) The contemporaneous appearance of cellular and acellular bone in heterostracans and osteostracans during the Ordovician provides no clue as to whether one is more primitive than the other.
Paleozoic
Definition:
(a.) Of or pertaining to, or designating, the older division of geological time during which life is known to have existed, including the Silurian, Devonian, and Carboniferous ages, and also to the life or rocks of those ages. See Chart of Geology.
Example Sentences:
(1) The geographic location of leptospirosis presents a pattern which closely parallels the distribution of Paleozoic bedrock.
(2) In general, the small subunit nuclear sequences appear to be best for elucidating Precambrian divergences, the large subunit nuclear sequences for Paleozoic and Mesozoic divergences, and the organellar sequences of both subunits for Cenozoic divergences.
(3) Recent work on Silurian, Devonian and Carboniferous terrestrial assemblages has provided plausible evidence for all major groups of extant fungi in the Paleozoic.
(4) Of the suborders present in the Paleozoic, seven are morphologically relatively simple, slowly evolving, and continued into Mesozoic and Cenozoic times to become the ancestoral lineages from which evolved several additional post-Paleozoic suborders.
(5) Key events in fungal macroevolution thus probably took place in the early Paleozoic or the late Precambrian, and the likelihood of finding definitive fossil evidence for them is small.
(6) The approximately 300 million years that make up Paleozoic time saw the evolution of eight of the fifteen recognized suborders of Foraminifera.
(7) The preliminary implication of these observations is that the mechanism of physiological color change involving MCH and its melanophore receptors evolved near the end of the Paleozoic or during the early Mesozoic, just before or early in the evolution of neopterygian (holostean and teleostean) fishes.
(8) Their early representatives may have given rise to three and eventually four post-Paleozoic suborders.
(9) The widespread late Paleozoic condition of seasonal drought favored progressive developments which, with the attainment of a reptilian stage, had the happy accidental result of the vertebrate conquest of the land, a conquest aided by the emergence of the insects as a basic food supply.
(10) A number of suborders in the Paleozoic have similar, supposedly independent, early evolutionary patterns with the following series of morphological steps: (1) single chambers with or without apertures depending on the amount of wall cement; (2) groups of chambers that appear to be buds or aggregations of individuals rather than true chambers; (3) a proloculus followed by a tubular second chamber that is first erect and gradually evolves into enrolled free-living individuals; (4) development of constrictions in the tubular chamber; and finally (5) evolution of true chambers.
(11) Fusulinines became extinct at the end of the Paleozoic.
(12) In Ontario, bedrock composed of limestone and dolomite formed in the Paleozoic era appears to be a reliable ecological marker for Leptospira pomona infection.
(13) In contrast, an eighth Paleozoic suborder, the Fusulinina, was an abundant, ecologically dominant group that evolved from simple to highly specialized forms and had a history of rapid evolution with diverse lineages.
(14) Antibodies to L. hardjo and L. sejroe occur in many bovine sera from a predominantly Precambrian area where Paleozoic outliers are numerous.
(15) A marked increase in atmospheric oxygen level near the beginning of the Paleozoic would eliminate oxygen-collagen priorities simultaneously and on a world-wide basis in all metazoan stocks providing evolutionary pressure for enlarged musculatures and associated "hard parts."