68-417: Pachycephalosaurus ( / ˌ p æ k ɪ ˌ s ɛ f əl ə ˈ s ɔː r ə s / ; meaning "thick-headed lizard", from Greek pachys-/ παχύς- "thickness", kephalon/ κεφαλή "head" and sauros/ σαῦρος "lizard") is a genus of pachycephalosaurid ornithischian dinosaur . The type species , P. wyomingensis , is the only known species , but some researchers argue that Stygimoloch might be
136-543: A pitch accent . In Modern Greek, all vowels and consonants are short. Many vowels and diphthongs once pronounced distinctly are pronounced as /i/ ( iotacism ). Some of the stops and glides in diphthongs have become fricatives , and the pitch accent has changed to a stress accent . Many of the changes took place in the Koine Greek period. The writing system of Modern Greek, however, does not reflect all pronunciation changes. The examples below represent Attic Greek in
204-530: A bulky body, long legs, and a heavy tail that was likely held rigid by ossified tendons . Pachycephalosaurus gives its name to Pachycephalosauria , a clade of herbivorous ornithischian dinosaurs that lived during the Late Cretaceous period in North America and Asia. Pachycephalosaurs were a part of Marginocephalia , thus being likely more closely related to the ceratopsians than
272-447: A different species, P. spinifer . This idea has been regarded as a way of interpretation by Mark Witton and Thomas Holtz. A phylogenetic analysis from 2021 by Evans and colleagues accepted the validity of the genus Stygimoloch on the basis of it being found in later rock layers than Pachycephalosaurus , but agreed with the consensus that Dracorex represents an ontogimorph of either Stygimoloch or Pachycephalosaurus instead of
340-508: A distinct taxon. However, David Evans himself noted in a Twitter post that he and his colleagues would also consider Stygimoloch as P. spinifer . Phylogenetic analyses by Evans and colleagues have been used to resolve the relationships within Pachycephalosauyridae, consistently finding Pachycephalosaurus as one of the most derived taxa closer to Prenocephale and Sphaerotholus than Stegoceras . The version of
408-562: A domed parietal attributable to Pachycephalosaurus were discovered in the Scollard Formation of Alberta , implying that the dinosaurs of this era were cosmopolitan and did not have discrete faunal provinces. The anatomy of Pachycephalosaurus itself is poorly known, as only skull remains have been described. Pachycephalosaurus is famous for having a large, bony dome on top of its skull, up to 25 cm (10 in) thick, which safely cushioned its brain. The dome's rear aspect
476-477: A lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period. They have the same general outline but differ in some of the detail. The only attested dialect from this period is Mycenaean Greek , but its relationship to the historical dialects and
544-419: A lesser degree. Pamphylian Greek , spoken in a small area on the southwestern coast of Anatolia and little preserved in inscriptions, may be either a fifth major dialect group, or it is Mycenaean Greek overlaid by Doric, with a non-Greek native influence. Regarding the speech of the ancient Macedonians diverse theories have been put forward, but the epigraphic activity and the archaeological discoveries in
612-404: A mixed diet of leaves , seeds , and fruits . The sharp, serrated teeth would have been very effective for shredding plants. It has also been suspected to a degree that it may have included meat in its diet. The most complete fossil jaw shows that it had serrated blade-like front teeth, reminiscent of those of carnivorous theropods. Nearly all Pachycephalosaurus fossils have been recovered from
680-616: A nearly complete skull from the Hell Creek Formation of Ekalaka , Carter County , Montana. P. reinheimeri was based on what is now DMNS 469, a dome and a few associated elements from the Lance Formation of Corson County , South Dakota. They also referred the older species "Troodon" wyomingensis to their new genus. Their two newer species have been considered synonymous with P. wyomingensis since 1983 . In 2015 , some pachycephalosaurid material and
748-678: A number of years. However, in 2007 , they were proposed to be juvenile or female morphologies of Pachycephalosaurus . At that year's meeting of the Society of Vertebrate Paleontology , Jack Horner of Montana State University presented evidence, from analysis of the skull of the Dracorex specimen, that it may be a juvenile form of Stygimoloch . In addition to this, he presented data that indicates that both Stygimoloch and Dracorex may be juvenile forms of Pachycephalosaurus . Horner and M.B. Goodwin published their findings in 2009 , showing that
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#1732798259334816-550: A prefix /e-/, called the augment . This was probably originally a separate word, meaning something like "then", added because tenses in PIE had primarily aspectual meaning. The augment is added to the indicative of the aorist, imperfect, and pluperfect, but not to any of the other forms of the aorist (no other forms of the imperfect and pluperfect exist). The two kinds of augment in Greek are syllabic and quantitative. The syllabic augment
884-427: A reptile or an armadillo -like animal. It became known as Tylosteus . Its actual nature was not revealed until Baird studied it again over a century later and identified it as a squamosal (bone from the back of the skull) of Pachycephalosaurus , including a set of bony knobs corresponding to those found on other specimens of Pachycephalosaurus . Because the name Tylosteus predates Pachycephalosaurus , according to
952-521: A rival directly, using intimidation displays to cow its rival. If intimidation failed, the Pachycephalosaurus would bend its head downward and to the side, striking the rival on its flank. This hypothesis is supported by the relatively broad torso of most pachycephalosaurs, which would have protected vital organs from trauma. The flank-butting theory was first proposed by Sues in 1978 and expanded upon by Ken Carpenter in 1997 . In 2012 ,
1020-567: A second species, P. spinifer , or a juvenile specimen of P. wyomingensis . It lived during the Maastrichtian age of the Late Cretaceous period in what is now western North America . Remains have been excavated in Montana , South Dakota , Wyoming , and Alberta . The species is known mainly from a single skull, plus a few extremely thick skull roofs (at 22 cm or 9 in thick). More complete fossils would come to be found in
1088-608: A separate historical stage, though its earliest form closely resembles Attic Greek , and its latest form approaches Medieval Greek . There were several regional dialects of Ancient Greek; Attic Greek developed into Koine. Ancient Greek was a pluricentric language , divided into many dialects. The main dialect groups are Attic and Ionic , Aeolic , Arcadocypriot , and Doric , many of them with several subdivisions. Some dialects are found in standardized literary forms in literature , while others are attested only in inscriptions. There are also several historical forms. Homeric Greek
1156-505: A single tooth (YPM 4810), also collected by Hatcher from the Lance. The tooth was named Palaeoscinus latus , but in 1990 , Coombs found the tooth to be from a pachycephalosaurid , possibly even Pachycephalosaurus itself. Hatcher also collected several additional teeth and skull fragments while working for Marsh, though these have yet to be described. P. wyomingensis , the type and currently only valid species of Pachycephalosaurus ,
1224-630: A standard subject of study in educational institutions of the Western world since the Renaissance . This article primarily contains information about the Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period ( c. 300 BC ), Ancient Greek was followed by Koine Greek , which is regarded as
1292-497: A study showed that cranial pathologies in a P. wyomingensis specimen were likely due to agonistic behavior . It was also proposed that similar damage in other pachycephalosaur specimens (previously explained as taphonomic artifacts and bone absorptions) may instead have been due to such behavior. Peterson et al. (2013) studied cranial pathologies among Pachycephalosauridae and found that 22% of all domes examined had lesions that are consistent with osteomyelitis , an infection of
1360-510: A vowel or /n s r/ ; final stops were lost, as in γάλα "milk", compared with γάλακτος "of milk" (genitive). Ancient Greek of the classical period also differed in both the inventory and distribution of original PIE phonemes due to numerous sound changes, notably the following: The pronunciation of Ancient Greek was very different from that of Modern Greek . Ancient Greek had long and short vowels ; many diphthongs ; double and single consonants; voiced, voiceless, and aspirated stops ; and
1428-570: Is a literary form of Archaic Greek (derived primarily from Ionic and Aeolic) used in the epic poems , the Iliad and the Odyssey , and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic and other Classical-era dialects. The origins, early form and development of the Hellenic language family are not well understood because of
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#17327982593341496-418: Is added to stems beginning with consonants, and simply prefixes e (stems beginning with r , however, add er ). The quantitative augment is added to stems beginning with vowels, and involves lengthening the vowel: Some verbs augment irregularly; the most common variation is e → ei . The irregularity can be explained diachronically by the loss of s between vowels, or that of the letter w , which affected
1564-666: Is called 'East Greek'. Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian Greek had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, as exemplified in the poems of the Boeotian poet Pindar who wrote in Doric with a small Aeolic admixture. Thessalian likewise had come under Northwest Greek influence, though to
1632-448: Is considered by some linguists to have been closely related to Greek . Among Indo-European branches with living descendants, Greek is often argued to have the closest genetic ties with Armenian (see also Graeco-Armenian ) and Indo-Iranian languages (see Graeco-Aryan ). Ancient Greek differs from Proto-Indo-European (PIE) and other Indo-European languages in certain ways. In phonotactics , ancient Greek words could end only in
1700-550: Is more like the corresponding bone of Dracorex than that of Pachycephalosaurus . The issue is of uncertain importance, though, if Dracorex actually represents a juvenile Pachycephalosaurus , as has been recently proposed. In 1890 , during the Bone Wars between Othniel Charles Marsh and Edward Drinker Cope , one of Marsh's collectors, John Bell Hatcher , collected a partial left squamosal ( YPM VP 335) later referred to Stygimoloch spinifer near Lance Creek, Wyoming , in
1768-550: Is the largest-known pachycephalosaur, known for having an extremely thick, slightly domed skull roof; visually, the structure of the skull suggests a ‘ battering ram ' function in life, evolved for use as a defensive mechanism or intra-species combat, similar to what is seen with today's bighorn sheep or muskoxen (with male animals routinely charging and head-butting each other for dominance). This hypothesis has actually been highly disputed in recent years. Remains attributable to Pachycephalosaurus may have been found as early as
1836-759: The Greek region of Macedonia during the last decades has brought to light documents, among which the first texts written in Macedonian , such as the Pella curse tablet , as Hatzopoulos and other scholars note. Based on the conclusions drawn by several studies and findings such as Pella curse tablet , Emilio Crespo and other scholars suggest that ancient Macedonian was a Northwest Doric dialect , which shares isoglosses with its neighboring Thessalian dialects spoken in northeastern Thessaly . Some have also suggested an Aeolic Greek classification. The Lesbian dialect
1904-512: The International Code of Zoological Nomenclature Tylosteus would normally be preferred. In 1985, Baird successfully petitioned to have Pachycephalosaurus used instead of Tylosteus because the latter name had not been used for over fifty years, was based on undiagnostic materials, and had poor geographic and stratigraphic information. This may not be the end of the story, however. Robert Sullivan suggested in 2006 that ANSP 8568
1972-481: The Lance Formation and Hell Creek Formation of the northwestern United States. Pachycephalosaurus possibly coexisted alongside additional pachycephalosaur species of the genera Sphaerotholus , as well as Dracorex and Stygimoloch , though these last two genera may represent different growth stages of Pachycephalosaurus itself. Other dinosaurs that shared its time and place include Thescelosaurus ,
2040-599: The hadrosaurid Edmontosaurus and a possible species of Parasaurolophus , ceratopsians like Triceratops , Torosaurus , Nedoceratops , Tatankaceratops , and Leptoceratops , the ankylosaurid Ankylosaurus , the nodosaurids Denversaurus and Edmontonia , and the theropods Acheroraptor , Dakotaraptor , Ornithomimus , Struthiomimus , Anzu , Leptorhynchos , Pectinodon , Paronychodon , Richardoestesia , and Tyrannosaurus . Ancient Greek Ancient Greek ( Ἑλληνῐκή , Hellēnikḗ ; [hellɛːnikɛ́ː] ) includes
2108-672: The ornithopods . Pachycephalosaurus is the most famous member of Pachycephalosauria, even if it is not the best-preserved member. The clade also includes Stenopelix , Wannanosaurus , Goyocephale , Stegoceras , Homalocephale , Tylocephale , Sphaerotholus , and Prenocephale . Within the tribe Pachycephalosaurini , Pachycephalosaurus is most closely related to Alaskacephale . Dracorex and Stygimoloch have also been synonymized with Pachycephalosaurus . In 2010 , Gregory S. Paul proposed that, while Stygimoloch and Dracorex possibly represent different growth stages of Pachycephalosaurus , Stygimoloch might represent
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2176-501: The present , future , and imperfect are imperfective in aspect; the aorist , present perfect , pluperfect and future perfect are perfective in aspect. Most tenses display all four moods and three voices, although there is no future subjunctive or imperative. Also, there is no imperfect subjunctive, optative or imperative. The infinitives and participles correspond to the finite combinations of tense, aspect, and voice. The indicative of past tenses adds (conceptually, at least)
2244-531: The 1850s. As determined by Donald Baird , in 1859 or 1860 , Ferdinand Vandeveer Hayden , an early fossil collector in the American West, collected a bone fragment in the vicinity of the head of the Missouri River , from what is now known to be the Lance Formation of southeastern Montana. This specimen, ANSP 8568, was described by Joseph Leidy in 1872 as belonging to the dermal armor of
2312-1031: The 5th century BC. Ancient pronunciation cannot be reconstructed with certainty, but Greek from the period is well documented, and there is little disagreement among linguists as to the general nature of the sounds that the letters represent. /oː/ raised to [uː] , probably by the 4th century BC. Greek, like all of the older Indo-European languages , is highly inflected. It is highly archaic in its preservation of Proto-Indo-European forms. In ancient Greek, nouns (including proper nouns) have five cases ( nominative , genitive , dative , accusative , and vocative ), three genders ( masculine , feminine , and neuter ), and three numbers (singular, dual , and plural ). Verbs have four moods ( indicative , imperative , subjunctive , and optative ) and three voices (active, middle, and passive ), as well as three persons (first, second, and third) and various other forms. Verbs are conjugated through seven combinations of tenses and aspect (generally simply called "tenses"):
2380-495: The Archaic period of ancient Greek (see Homeric Greek for more details): Μῆνιν ἄειδε, θεά, Πηληϊάδεω Ἀχιλῆος οὐλομένην, ἣ μυρί' Ἀχαιοῖς ἄλγε' ἔθηκε, πολλὰς δ' ἰφθίμους ψυχὰς Ἄϊδι προΐαψεν ἡρώων, αὐτοὺς δὲ ἑλώρια τεῦχε κύνεσσιν οἰωνοῖσί τε πᾶσι· Διὸς δ' ἐτελείετο βουλή· ἐξ οὗ δὴ τὰ πρῶτα διαστήτην ἐρίσαντε Ἀτρεΐδης τε ἄναξ ἀνδρῶν καὶ δῖος Ἀχιλλεύς. The beginning of Apology by Plato exemplifies Attic Greek from
2448-601: The Classical period of ancient Greek. (The second line is the IPA , the third is transliterated into the Latin alphabet using a modern version of the Erasmian scheme .) Ὅτι [hóti Hóti μὲν men mèn ὑμεῖς, hyːmêːs hūmeîs, 1890 in paleontology Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils . This includes
2516-519: The Lance Formation. Marsh described the squamosal along with the dermal armor of Denversaurus as the body armor of Triceratops in 1892 , believing that the squamosal was a spike akin to the plates on Stegosaurus . The squamosal spike was even featured in Charles Knight 's painting of Cope's ceratopsid Agathaumas , likely based on Marsh's hypothesis. Marsh also named a species of now- dubious ankylosaur Palaeoscincus in 1892 based on
2584-554: The analysis published by Woodruff and colleagues in 2023 is below. Wannanosaurus Hanssuesia Colepiocephale Stegoceras validum Stegoceras novomexicanum Goyocephale Homalocephale Tylocephale Foraminacephale Amtocephale Acrotholus Prenocephale Alaskacephale Stygimoloch Pachycephalosaurus S. goodwini S. lyonsi S. triregnum S. buchholtzae S. edmontonensis Aside from Pachycephalosaurus itself, two other pachycephalosaurs were described from
2652-550: The aorist. Following Homer 's practice, the augment is sometimes not made in poetry , especially epic poetry. The augment sometimes substitutes for reduplication; see below. Almost all forms of the perfect, pluperfect, and future perfect reduplicate the initial syllable of the verb stem. (A few irregular forms of perfect do not reduplicate, whereas a handful of irregular aorists reduplicate.) The three types of reduplication are: Irregular duplication can be understood diachronically. For example, lambanō (root lab ) has
2720-419: The augment when it was word-initial. In verbs with a preposition as a prefix, the augment is placed not at the start of the word, but between the preposition and the original verb. For example, προσ(-)βάλλω (I attack) goes to προσ έ βαλoν in the aorist. However compound verbs consisting of a prefix that is not a preposition retain the augment at the start of the word: αὐτο(-)μολῶ goes to ηὐ τομόλησα in
2788-419: The back of the skull. As the animal grew, the horns shrunk and rounded out as the dome grew. Pachycephalosaurus was bipedal and possibly the largest of all pachycephalosaurids. It has been estimated that Pachycephalosaurus was about 4.5 metres (14.8 ft) long and weighed about 370–450 kilograms (820–990 lb). Based on other pachycephalosaurids, it probably had a fairly short, thick neck, short arms,
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2856-423: The bone resulting from penetrating trauma or trauma to the tissue overlying the skull that lead to an infection of the bone tissue. This high rate of pathology lends more support to the hypothesis that pachycephalosaurid domes were employed in intra-specific combat. Pachycephalosaurus wyomingensis specimen BMR P2001.4.5 was observed to have 23 lesions in its frontal bone and P. wyomingensis specimen DMNS 469
2924-438: The center of Greek scholarship, this division of people and language is quite similar to the results of modern archaeological-linguistic investigation. One standard formulation for the dialects is: West vs. non-West Greek is the strongest-marked and earliest division, with non-West in subsets of Ionic-Attic (or Attic-Ionic) and Aeolic vs. Arcadocypriot, or Aeolic and Arcado-Cypriot vs. Ionic-Attic. Often non-West
2992-553: The cervical and anterior dorsal vertebrae show that the neck was carried in an S- or U-shaped curve, rather than a straight orientation and that it might have been unfit for transmitting stress from direct head-butting. Lastly, the rounded shape of the skull would lessen the contacted surface area during head-butting, resulting in glancing blows. Alternatively, Pachycephalosaurus and other pachycephalosaurids may have engaged in flank-butting during intraspecific combat. In this scenario, an individual may have stood roughly parallel or faced
3060-615: The dialect of Sparta ), and Northern Peloponnesus Doric (including Corinthian ). All the groups were represented by colonies beyond Greece proper as well, and these colonies generally developed local characteristics, often under the influence of settlers or neighbors speaking different Greek dialects. After the conquests of Alexander the Great in the late 4th century BC, a new international dialect known as Koine or Common Greek developed, largely based on Attic Greek , but with influence from other dialects. This dialect slowly replaced most of
3128-423: The family Troodontidae , a misconception which was not corrected until 1945 by Charles M. Sternberg . In 1943 , Barnum Brown and Erich Maren Schlaikjer , with newer, more complete material, established the genus Pachycephalosaurus . They named two species: Pachycephalosaurus grangeri , the type species of their new genus, and Pachycephalosaurus reinheimeri . P. grangeri was based on AMNH 1696,
3196-540: The following years. Pachycephalosaurus was among the last species of non-avian dinosaurs on Earth before the Cretaceous–Paleogene extinction event . The genus Tylosteus has been synonymized with Pachycephalosaurus , as have the genera Stygimoloch and Dracorex , in recent studies. Like other pachycephalosaurids, Pachycephalosaurus was a bipedal herbivore , possessing long, strong legs and somewhat small arms with five-fingered hands. Pachycephalosaurus
3264-673: The forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek ( c. 1400–1200 BC ), Dark Ages ( c. 1200–800 BC ), the Archaic or Epic period ( c. 800–500 BC ), and the Classical period ( c. 500–300 BC ). Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers . It has contributed many words to English vocabulary and has been
3332-430: The frequency of lesion distribution and the bone structure of frontoparietal domes lends strong support to the hypothesis that pachycephalosaurids used their unique cranial structures for agonistic behavior. CT scan comparisons of the skulls of Stegoceras validum , Prenocephale prenes , and several head-striking artiodactyls have also supported pachycephalosaurids as being well-equipped for head-butting. Micro-CT scans of
3400-561: The historical Dorians . The invasion is known to have displaced population to the later Attic-Ionic regions, who regarded themselves as descendants of the population displaced by or contending with the Dorians. The Greeks of this period believed there were three major divisions of all Greek people – Dorians, Aeolians, and Ionians (including Athenians), each with their own defining and distinctive dialects. Allowing for their oversight of Arcadian, an obscure mountain dialect, and Cypriot, far from
3468-476: The historical circumstances of the times imply that the overall groups already existed in some form. Scholars assume that major Ancient Greek period dialect groups developed not later than 1120 BC, at the time of the Dorian invasions —and that their first appearances as precise alphabetic writing began in the 8th century BC. The invasion would not be "Dorian" unless the invaders had some cultural relationship to
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#17327982593343536-540: The hypothesis that all flat-skulled pachycephalosaur species were juveniles of the dome-headed adults, such as Goyocephale and Homalocephale . The discovery of baby skulls assigned to Pachycephalosaurus that were described in 2016 from two different bone beds in the Hell Creek Formation has been presented as further evidence for this hypothesis. The fossils, as described by David Evans and Mark Goodwin et al are identical to all three supposed genera in
3604-421: The idea of P. spinifer . It has been widely hypothesized for decades that Pachycephalosaurus and its relatives were the ancient, bipedal equivalents of bighorn sheep or musk oxen , where male individuals would ram each other headlong and that they would horizontally straighten their head, neck, and body in order to transmit stress during ramming. However, there have also been alternative suggestions that
3672-485: The latest Cretaceous of the northwestern United States: Stygimoloch spinifer ("thorny Moloch of the Styx ") and Dracorex hogwartsia ("dragon king of Hogwarts "). The former is only known from a juvenile skull with a reduced dome and large spikes, while the latter, also known from only a juvenile skull, had a seemingly flat head with short horns. Due to their unique head ornamentation, they were seen as separate species for
3740-508: The older dialects, although the Doric dialect has survived in the Tsakonian language , which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek . By about the 6th century AD, the Koine had slowly metamorphosed into Medieval Greek . Phrygian is an extinct Indo-European language of West and Central Anatolia , which
3808-411: The pachycephalosaurid specimen, identified as cf. Foraminacephale brevis , also support that pachycephalosaurids likely engaged in head-butting. Scientists do not yet know what these dinosaurs ate. Having very small, ridged teeth, they could not have chewed tough, fibrous plants like flowering shrubs as effectively as other dinosaurs of the same period. It is assumed that pachycephalosaurs lived on
3876-412: The pachycephalosaurs could not have used their domes in this way. The primary argument that has been raised against head-butting is that the skull roof may not have adequately sustained impact associated with ramming, as well as a lack of definitive evidence of scars or other damage on fossilized Pachycephalosaurus skulls. However, more recent analyses have uncovered such damage (see below). Furthermore,
3944-487: The perfect stem eilēpha (not * lelēpha ) because it was originally slambanō , with perfect seslēpha , becoming eilēpha through compensatory lengthening. Reduplication is also visible in the present tense stems of certain verbs. These stems add a syllable consisting of the root's initial consonant followed by i . A nasal stop appears after the reduplication in some verbs. The earliest extant examples of ancient Greek writing ( c. 1450 BC ) are in
4012-451: The placement of the rugose knobs on their skulls, and the unique features of Stygimoloch and Dracorex are thus instead morphologically consistent features on a Pachycephalosaurus growth curve. It has been noted that morphological differences between Stygimoloch and Pachycephalosaurus may also partly be due to slight stratigraphic differences. The few Stygimoloch specimens that have reliable stratigraphic data were all collected from
4080-532: The spike and skull dome bones of all three "species" exhibit extreme plasticity and that both Dracorex and Stygimoloch are known only from juvenile specimens, while Pachycephalosaurus is known only from adult specimens. These observations, in addition to the fact that all three forms lived in the same time and place, led them to conclude that Dracorex and Stygimoloch were simply juvenile Pachycephalosaurus , which lost spikes and grew domes as they aged. A 2010 study by Nick Longrich and colleagues also supported
4148-411: The study of body fossils, tracks ( ichnites ), burrows , cast-off parts, fossilised feces ( coprolites ), palynomorphs and chemical residues . Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science . This article records significant discoveries and events related to paleontology that occurred or were published in
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#17327982593344216-517: The syllabic script Linear B . Beginning in the 8th century BC, however, the Greek alphabet became standard, albeit with some variation among dialects. Early texts are written in boustrophedon style, but left-to-right became standard during the classic period. Modern editions of ancient Greek texts are usually written with accents and breathing marks , interword spacing , modern punctuation , and sometimes mixed case , but these were all introduced later. The beginning of Homer 's Iliad exemplifies
4284-475: The upper part of the Hell Creek Formation, whereas Pachycephalosaurus morphs were all collected from the lower part. This has also led to suggestions that Stygimoloch might represent its own species, P. spinifer . In their 2021 redescription of Sinocephale bexelli , Evans and his colleageues treated Stygimoloch (but not Dracorex ) as a separate taxon based on their phylogenetic analysis. However, Evans himself has noted that he and his colleagues support
4352-480: Was Aeolic. For example, fragments of the works of the poet Sappho from the island of Lesbos are in Aeolian. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, or to an island. Doric notably had several intermediate divisions as well, into Island Doric (including Cretan Doric ), Southern Peloponnesus Doric (including Laconian ,
4420-485: Was an absence of pathology. This would support the hypothesis that these individuals represent either females or juveniles, where intra-specific combat behavior is not expected. Histological examination reveals that pachycephalosaurid domes are composed of a unique form of fibrolamellar bone that contains fibroblasts , which play a critical role in wound healing and are capable of rapidly depositing bone during remodeling. Peterson et al. (2013) concluded that, taken together,
4488-542: Was edged with bony knobs and short bony spikes projected upwards from the snout. However, the spikes were probably blunted, not sharp. The skull was short and possessed large, rounded eye sockets that faced forward, suggesting that the animal had binocular vision . Pachycephalosaurus had a small muzzle that ended in a pointed beak. The teeth were tiny, with leaf-shaped crowns. The head was supported by an S- or U-shaped neck. Younger individuals of Pachycephalosaurus might have had flatter skulls and larger horns projecting from
4556-436: Was named by Charles W. Gilmore in 1931 . He coined it for the partial skull USNM 12031, from the Lance Formation of Niobrara County , Wyoming . Gilmore assigned his new species to Troodon as T. wyomingensis . At the time, paleontologists thought that Troodon , then known only from teeth, was the same as Stegoceras , which had similar teeth. Accordingly, what are now known as pachycephalosaurids were assigned to
4624-427: Was observed to have 5 lesions. The frequency of trauma was comparable across the different genera in the pachycephalosaurid family , despite the fact that these genera vary with respect to the size and architecture of their domes and the fact that they existed during varying geologic periods. These findings were in stark contrast with the results from analysis of the relatively flat-headed pachycephalosaurids, where there
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