It has been a long-held belief that, as a result of hunting habits, early humans were partly or even primarily responsible for the decline and eventual extinction of most of the largest mammalian species that inhabited ancient Africa. These large plant-eating mammals, called megaherbivores and weighing more than 1000 kg (2200 lb) each, displayed an incredible biodiversity and numbered more than 30 species in the past, but only a handful remain today: the hippopotamus, the black rhinoceros and white rhinoceros, four species of giraffe, and two species of African elephants (the larger African bush elephant and the smaller African forest elephant). However, more detailed analyses of the parameters and factors involved in the demise of ancient African megaherbivores suggest that humans did not cause the extinction of these mammals. Instead, changes in the ancient climate of Africa, in addition to the concomitant changes in African ecosystems and food sources, led to the extinction of the majority of these creatures. See also: Africa; African mammals; Animal evolution; Biodiversity; Elephant; Extinction; Giraffe; Global climate change; Hippopotamus; Proboscidea; Rhinoceros

Conifers are predominantly cone-bearing, evergreen trees and shrubs belonging to the order Pinales, as well as a small number of extinct orders, in the class Pinopsida of the division Pinophyta (Coniferophyta). All are woody plants, and they are often the predominant trees of forests worldwide, including pine, spruce, fir, hemlock, cedar, larch, juniper, cypress, yew, and redwood species. Because the ovules (young seeds) of these plants are exposed directly to the air at the time of pollination—that is, these plants produce seeds that are not enclosed in a fruit or ovary—conifers are classified as gymnosperms. (In contrast, the flowering plants, or angiosperms, have ovules enclosed in an ovary.) Today, conifers constitute the principal source of lumber and pulp for paper and wood products. See also: Forest and forestry; Forest timber resources; Lumber; Pinales; Pinophyta; Pinopsida; Tree; Wood products

At the Woranso-Mille paleontological site in northern Ethiopia, researchers have discovered a 3.8 million-year-old cranium (skull) belonging to a primitive hominin known as Australopithecus anamensis. Initially unearthed in 2016, but not reported until dating and other analyses were completed in 2019, the well-preserved fossil is the first skull of this particular species to be found. Paleoanthropologists expect that this discovery will reshape the ancient timeline of human evolutionary history because it reveals the previously unknown facial features of A. anamensis, which now can be compared to the facial morphologies of other ancient hominins. The fossil evidence also opens up the possibility of the coexistence of two early hominins—A. anamensis and A. afarensis—in the same area of Ethiopia. Prior to this cranium discovery, these two species were assumed to have emerged consecutively along a more linear chronology. See also: Anthropology; Australopith; Dating methods; Earliest hominins; Fossil; Fossil humans; Paleontology; Physical anthropology

The evolutionary ancestry of the modern human race became even more complicated in 2012 with the results of studies on DNA extracted from bits of 50,000-year-old bone from Siberia. The analysis confirmed that an archaic species of people called Denisovans—contemporaries of Neandertals who were unknown to science until 20120—are indeed ancestors of many people living today. See also: Denisovans; DNA unveils enigmatic Denisovans; Neandertals

In the Rising Star cave system in South Africa, located about 48 kilometers (30 miles) north of Johannesburg, paleoanthropologists have unearthed an extensive collection of more than 1550 skeletal elements from at least 15 individuals that have been provisionally assigned to a new species of the genus Homo. The location in which these numerous fossils were found is a highly inaccessible chamber known as the Dinaledi ("Star") Chamber; hence, this previously unknown offshoot of the hominin family has been given the name Homo naledi. This discovery has provided the largest morphologically homogeneous assemblage of a single species of ancient hominins yet found in Africa. See also: Anthropology; Fossil; Physical anthropology

Dogs belong to the mammalian family Canidae. Members of this carnivorous group comprise domestic dogs, wolves, wild dogs, coyotes, dingoes, foxes, and jackals. Canis lupus familiaris (also referred to as Canis familiaris) is the species name given to all breeds of domestic dogs. The exact origin of domestic dogs has been a controversial topic, but the preponderance of genetic and fossil evidence points to a close relationship to the wolf (Canis lupus). The earliest evidence of ancient dogs has come from fossils excavated from the Goyet cave in Belgium, the site of Předmostí in the Czech Republic, and the Altai Mountains in Siberia. Some of these fossil remains are more than 36,000 years old. See also: Breeding (animal); Carnivora; Carnivoran evolution; Dogs; Domestication (anthropology); Fossil; Mammalia

Genealogists and anthropologists have long disputed the provenance of domestic dogs (Canis lupus familiaris). Although genetic analyses and fossil evidence indicate that the domestic dog descended from the gray wolf (Canis lupus), the exact location (or locations) and time (or times) of origin for canine domestication are contentious topics. Southeast Asia and Europe have often been noted as early centers for the domestication of dogs, with most researchers assigning a probable range of dates between 15,000 and 32,000 years ago as the time for dog domestication. However, a recent study pinpoints northern Siberia as the origin of the domestication of dogs and estimates that domestication took place approximately 23,000 years ago. Early domesticated dogs later dispersed eastward to the Americas and westward to Eurasia as ancient Siberian peoples migrated away from their original geographic homes. See also: Anthropology; Dogs; Domestication; Fossil; Phylogeny; Zooarcheology

Recent excavations in Asia unearthed a pristine, three-dimensional fossil of a tiny dinosaur tail with preserved feathers and soft tissues (presumably skin). In 2016, investigators in northern Myanmar (Burma) recovered a piece of Cretaceous-era amber (Fig. 1) containing an approximately 99-million-year-old feathered tail from a theropod dinosaur. (Theropods are carnivorous bipedal saurischian reptiles that first appeared in the Upper Triassic and culminated in the uppermost Cretaceous.) Although the size of the tail measures only 37 mm (1.46 in.), eight vertebrae can be identified, and the morphological structure of the plumage is clearly observable. See also: Amber; Cretaceous; Dinosauria; Fossil; Saurischia

The earliest representatives of modern humans—those belonging to Homo sapiens—evolved from more archaic humans approximately 150,000–300,000 years ago in eastern Africa. During succeeding years, the geographical range of anatomically modern humans expanded. In some cases, modern humans may have admixed with local archaic human populations; in other cases, they completely displaced archaic peoples. Then, about 70,000 to 60,000 years ago, H. sapiens dispersed from Africa in significant numbers, first spreading eastward into Asia. However, a portion of the population roamed northward into central Asia and then westward into Europe. Now, investigators in present-day Bulgaria have found the earliest evidence of H. sapiens in Europe, including a fossilized molar, six bone fragments, and various stone tools and ornaments that date back as early as 44,000–46,000 years ago. See also: Anthropology; Archeology; Bone; Dental anthropology; Early modern humans; Europe; Fossil; Physical anthropology; Tooth

In the Afar region of Ethiopia, paleoanthropologists unearthed a 2.8 million-year-old jawbone (mandible) that was provisionally assigned to the genus Homo [the genus of human beings, including modern humans (Homo sapiens) and other extinct species]. This fossil discovery, announced in the journal Science in 2015, is extremely important because it fills in a notable gap in the ancient timeline of human evolutionary history. See also: Anthropology; Fossil; Physical anthropology