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Outside the stele lies the endodermis, which is the innermost cell layer of the cortex. The concept of the stele was developed in the late 19th century by French botanists P. E. L. van Tieghem and H. Doultion as a model for understanding the relationship between the shoot and root, and for discussing the evolution of vascular plant morphology. [2]
Baal with Thunderbolt or the Baal stele is a white limestone bas-relief stele from the ancient kingdom of Ugarit in northwestern Syria. The stele was discovered in 1932, about 20 metres (66 ft) from the Temple of Baal in the acropolis of Ugarit, during excavations directed by French archaeologist Claude F. A. Schaeffer .
The evolution of biological complexity is one important outcome of the process of evolution. [1] Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.
The word phyletic derives from the Greek φυλετικός phūletikos, which conveys the meaning of a line of descent. [2] Phyletic gradualism contrasts with the theory of punctuated equilibrium, which proposes that most evolution occurs isolated in rare episodes of rapid evolution, when a single species splits into two distinct species, followed by a long period of stasis or non-change.
Two useful introductions to the fundamental theory underlying the unit of selection issue and debate, which also present examples of multi-level selection from the entire range of the biological hierarchy (typically with entities at level N-1 competing for increased representation, i.e., higher frequency, at the immediately higher level N, e.g., organisms in populations or cell lineages in ...
Based on these findings, Malmgren and colleagues introduced a new mode of evolution and proposed to call it "punctuated gradualism." [1] There is strong evidence supporting both gradual evolution of a species over time and rapid events of species evolution separated by periods of little evolutionary change. Organisms have a great propensity to ...
The evidence of plant evolution changes dramatically in the Ordovician with the first extensive appearance of embryophyte spores in the fossil record. The earliest terrestrial plants lived during the Middle Ordovician around 470 million years ago , based on their fossils found in the form of monads and spores, with resistant polymers in their ...
A Hakkari stele: An armed warrior man wearing a cap (1500-1000 BCE) Bronze Age anthropomorphic funerary stelae have been found in Saudi Arabia. There are similarities to the Kurgan type in the handling of the slab-like body with incised detail, though the treatment of the head is rather more realistic. [15]